EP1979089A1 - Process for the synthesis of product molecules - Google Patents

Process for the synthesis of product molecules

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Publication number
EP1979089A1
EP1979089A1 EP07703853A EP07703853A EP1979089A1 EP 1979089 A1 EP1979089 A1 EP 1979089A1 EP 07703853 A EP07703853 A EP 07703853A EP 07703853 A EP07703853 A EP 07703853A EP 1979089 A1 EP1979089 A1 EP 1979089A1
Authority
EP
European Patent Office
Prior art keywords
laser pulses
molecules
synthesis
gas
passed
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP07703853A
Other languages
German (de)
French (fr)
Inventor
Horst Weiss
Gustav Gerber
Patrick Henning NÜRNBERGER
Daniel Stephan Wolpert
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BASF SE
Original Assignee
BASF SE
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Filing date
Publication date
Application filed by BASF SE filed Critical BASF SE
Priority to EP07703853A priority Critical patent/EP1979089A1/en
Publication of EP1979089A1 publication Critical patent/EP1979089A1/en
Withdrawn legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J19/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J19/12—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor employing electromagnetic waves
    • B01J19/121—Coherent waves, e.g. laser beams
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
    • B01J3/006—Processes utilising sub-atmospheric pressure; Apparatus therefor
    • C—CHEMISTRY; METALLURGY
    • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
    • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
    • C10G2/00—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon
    • C10G2/30—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen
    • C10G2/32—Production of liquid hydrocarbon mixtures of undefined composition from oxides of carbon from carbon monoxide with hydrogen with the use of catalysts
    • C10G2/34—Apparatus, reactors
    • C10G2/341—Apparatus, reactors with stationary catalyst bed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0873—Materials to be treated
    • B01J2219/0875—Gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0873—Materials to be treated
    • B01J2219/0881—Two or more materials
    • B01J2219/0883—Gas-gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/08—Processes employing the direct application of electric or wave energy, or particle radiation; Apparatus therefor
    • B01J2219/0873—Materials to be treated
    • B01J2219/0892—Materials to be treated involving catalytically active material

Definitions

  • the invention relates to a process for the synthesis of product molecules, with which the course of chemical reactions can be controlled in a targeted manner.
  • Targeted control of chemical reactions on a molecular level is an old dream of chemistry.
  • the conventional macroscopic control parameters of chemistry such as temperature, concentration or pressure do not allow direct access to the quantum-mechanical reaction process.
  • many new findings in the field of quantum control have been gained, using specially designed light fields, which can be used to efficiently and selectively select specific reaction channels.
  • An experimental technique relies on the manipulation of femtosecond laser pulses by means of a pulse shaper. This technique is described, for example, in the review article by T. Brixner, G. Gerber: "Quantum Control of Gas-Phase and Liquid-Phase Femtochemistry", CHEMPHYSCHEM 2003, 4, 418-438.
  • the starting point is a laser pulse of a few femtoseconds duration (usually 10 to 150 fs), which can be generated by a commercial laser system.
  • this laser pulse is converted into a "shaped" laser pulse, wherein the shaping relates to the phases and / or amplitudes of the coherent spectral components, which need not be uniform, but can be modulated and are adapted to the reaction sequence to be optimized ,
  • the object of the present invention is to avoid the disadvantages of the prior art and in particular to enable a selective formation of molecular bonds with shaped ultrashort laser pulses.
  • This object is achieved by a method for the synthesis of product molecules, wherein ultrashort laser pulses formed with the aid of a pulse shaper are generated and a gas containing educt molecules is passed onto a surface on which the educt molecules are at least partially adsorbed, wherein the ultrashort formed Laser pulses are directed to the surface to control a reaction course for the synthesis of the product molecules from adsorbed on the surface of educts.
  • the product molecules are molecules whose yield can be specifically influenced by the shaped laser pulses. They are caused by chemical reactions of educts on the surface under the influence of laser pulses.
  • Ultrashort laser pulses in connection with the method according to the invention are laser pulses whose duration (as short as possible according to the time-bandwidth product) is in the range of one attosecond to 1 nanosecond, preferably in the range of 1 femtosecond to 10 picoseconds, particularly preferably in the range of 5 to 200 femtoseconds.
  • Such ultrashort laser pulses are provided in particular by commercial femtosecond lasers.
  • Synthesis in connection with the invention means the production of product molecules, in which new molecular bonds are formed and in which the educt molecules or the educts are not only broken down into their constituents. Furthermore, the synthesis of the product molecules in the present invention is preferably carried out by multimolecular reactions, in particular by bimolecular reactions.
  • a gas containing the educt molecules is passed to the surface on which they are at least partially adsorbed.
  • the shaped ultrashort laser pulses are directed onto the surface.
  • the educts adsorbed on the surface can thereby correspond to educt molecules from the gas conducted onto the surface or be smaller (dissociation process) or larger (aggregation) molecules or atoms resulting therefrom.
  • the shaped ultrashort laser pulses for the process of the present invention are shaped so that the reaction yield of the product molecules is maximized.
  • the shaped ultrashort laser pulses can also be shaped so that the reaction yield of a product deviating from the product molecules to be synthesized is minimized.
  • the process according to the invention for the synthesis of product molecules preferably proceeds by passing a continuous mass flow of gas with the educt molecules onto the surface and directing shaped ultrashort laser pulses onto the surface at a specific repetition rate.
  • the surface serves in the present invention for adsorbing the educts and therefore must have an affinity for the educt molecules in the gas.
  • the surface should at least physisorb the educt molecules or educts and if necessary even chemisorb them. In physisorption, the adsorbed Eduktmo- remain molecules in their original chemical state. In the case of chemisorption, however, the adsorbates form a chemical bond with the surface. The adsorbate can dissociate on the surface.
  • the use of the surface offers, inter alia, the advantage that a relatively high density of the educt substances is achieved. This results in a higher burst rate and higher yields. In the gas phase, the likelihood of multiple particles colliding would be far too low.
  • the surface may act, for example, as a catalyst for the dissociation or aggregation of eu duktmolekülen or the special nature of the (eg metallic) carrier is exploited, as for example in M. Bonn et al.,: “Phonon-Versus Electron-Mediated Desorption and Oxidation of CO on Ru (OOOI) ", SCIENCE 1999, 285, 1042-1045.
  • the shaped ultrashort laser pulses interact in the method according to the invention with the surface and the adsorbed educts for the synthesis of the product molecules.
  • the surface in addition to its function as a sorbent, the surface also performs the function of a catalyst which catalyzes the synthesis of the product molecules.
  • the pulse former shapes spectral components of laser pulses in terms of intensity (amplitude) and phase.
  • the unshaped laser pulses which emits, for example, a commercial femtosecond laser and in which all the spectral components occur at the same time, are converted by the pulse shaper into shaped laser pulses, which can have variably adjustable components of the different spectral colors at different times.
  • the pulse shaper the duration of a laser pulse is variable, provided that its spectral width allows the generation of a laser pulse in the desired time range.
  • the relative color components (intensity) and their temporal arrangement (phase) in the shaped ultrashort laser pulse directly influence the yield in the synthesis of the product molecules from educts adsorbed on the surface.
  • the pulse shaper forms spectral components of laser pulses with respect to polarization.
  • Another parameter for optimizing the laser pulse shape is given, by which the yield of product molecules can be increased.
  • the pulse shaper controls the polarization state of light on an ultrashort time scale.
  • Such a polarization pulse shaper preferably manipulates the transient intensity, the instantaneous frequency, the degree of ellipticity, and the orientation of the major elliptical axes in each individual ultrashort laser pulse.
  • a preferred embodiment of the method according to the invention is that during the synthesis, an optimization of the shaped ultrashort laser pulses by measuring by means of a detector, which products with what yields in the synthesis of the product molecules, generating a modified pulse shape by means of a computer by an optimization algorithm and Driving the pulse shaper, so that the shaped ultrashort laser pulses are generated with the changed pulse shape takes place.
  • This has the advantage that for the optimization of the product molecule synthesis no prior knowledge about the educt molecules / reactants, the surface or the course of the chemical reaction is required.
  • the computer (for example a personal computer) takes over the control of the pulse shaper and can, for example, optimize the reaction yield.
  • the iterative improvement of the laser pulse form proceeds as follows.
  • Ultrashort laser pulses are directed to the surface to initiate a reaction to synthesize the product molecules.
  • a detector is used to measure which products are produced at what yield. Any suitable detector known to the person skilled in the art and suitable for detecting the products can be used as the detector.
  • the detector is a detector based on at least one of the time-resolved detection methods selected from the group of time-of-flight mass spectroscopy, photoelectron spectroscopy, emission spectroscopy, and two-dimensional spectroscopy and four-wave mixing.
  • the computer processes the information determined by the detector on the yields of the various products.
  • the optimization algorithm generates improved pulse shapes of the laser pulses, which in turn are generated by the pulse shaper and directed to the surface for synthesis of the product molecules. This optimization procedure is repeated until synthesis of the product molecules is optimized, for example, to a maximum of the desired product molecule yield (selectivity) relative to the yield of an undesired product or to a minimum of relative yield (selectivity) of such undesired product.
  • the optimization algorithm used is preferably an evolutionary algorithm.
  • This computer algorithm is a self-learning process modeled on biological evolution. According to Darwin's principle "Survival of the fittest" (the best survived), laser pulses that particularly fulfill the optimization goal are selected and “propagated” by combination with similarly successful phase settings. Some of the “offspring” produced this way are better suited than their "ancestors” (they are given a higher “fitness”), and they are re-selected for reproduction. If this process of evolution is passed through for enough generations, then finally a laser pulse is found, which produces the optimal reaction result.
  • the laser pulses are formed by a pulse shaper based on a computer-controlled technique which drives at least one device selected from the group consisting of liquid crystal display, acousto-optic modulator, acousto-optic filter, deformable mirror and Micromirror arrangement comprises.
  • a laser pulse by means of a pulse shaper in terms of spectral intensity and phase, and polarization usually based on the fact that the laser pulse is split (for example by means of a grating or prisms) in its spectral components, from which a parallel beam is generated, as a "Phase shifter" acting causes a transit time difference of the spectral components and the beam is again focused and (for example, by another grid) is superimposed on a shaped laser pulse.
  • At least one liquid crystal display may serve as such a device acting as a "phase shifter," or else an acousto-optic filter, for which, however, no splitting of the spectral components is necessary ,
  • the manipulation of the pulse shape by means of a liquid crystal display is carried out by applying suitable electrical voltages to the individual LCD pixels, whereby the refractive indices can be chosen such that the different spectral components are delayed relative to one another as they propagate through the LCD.
  • the acousto-optic filter is based on another method, in which the light does not first have to be split into its spectral components. Rather, the light and an acoustic wave propagate through a special birefringent crystal. Each spectral component may be attached to the acoustic grating at a particular position in the crystal, e.g. be bent from a normal to an extraordinary ray. The resulting pulse therefore consists of the individual color components which have been diffracted at different times, whereby a phase modulation is possible.
  • the gas containing the educt molecules is passed onto a surface which is a metallic surface or a metal oxide surface and which preferably at least one element from one of the subgroups MIB to IIB (transition metals), more preferably from one of the groups VIIIB , IB and IIB of the Periodic Table of the Elements.
  • Preferred elements of Groups VIIIB, IB and IIB of the Periodic Table of the Elements are Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Cd, Os, Ir, Pt, Au and Hg.
  • the metals may also be present as an alloy or according to another embodiment, which is the Gas containing educt molecules is passed onto a surface which is a single-crystal surface of a transition metal, for example Pd (100), Pt (100) or Ag (11 1).
  • a transition metal for example Pd (100), Pt (100) or Ag (11 1).
  • the surface is a surface of a technical catalyst, for example a technical catalyst, which supports said elements supported or unsupported, pure, as alloys or as oxides.
  • the gas which is passed onto the surface in the method according to the invention contains one or more types of educt molecules.
  • product molecules can be synthesized by a polymerization reaction from only one kind of starting material molecules.
  • it contains a mixture of at least two types of educt molecules, wherein a ratio of mass flows of the at least two types of educt molecules can be regulated by a control device.
  • the ratio of the mass flows, as well as the pulse shape of the shaped laser pulses, has an influence on the yield of the product molecules in carrying out the method according to the invention.
  • a control device can therefore regulate the mass flows of the at least two types of educt molecules in such a way that a certain maximum yield of the product molecules is achieved.
  • a gas is passed to the surface, the at least one kind of Eduktmolekülen selected from the group acetone, acetylene, formic acid, ammonia, arsine, hydrocyanic acid, boron trichloride, boron trifluoride, bromothene, bromomethane, hydrogen bromide, 1.3-butadiene , Butane, 1-butene, 1-butyne, chlorine, chlorodifluoromethane, chloroethene, chloromethane, hydrogen chloride, cis-2-butene, deuterium, dichlorosilane, diethyl ether, difluoromethane, dimethylamine, dimethyl ether, 2,2-dimethylpropane, disilane, nitrous oxide, nitrous oxide , Ethane, ethene, ethylene oxide, fluoromethane, formaldehyde, hexafluoroethane,
  • the gas containing the educt molecules is conducted onto the surface in a vacuum chamber.
  • the vacuum chamber there is preferably a vacuum ⁇ 10 "3 mbar, in particular ⁇ 10 " 4 mbar, when the gas is supplied to the surface.
  • Figure 1 shows schematically an arrangement for carrying out the method according to the invention for the synthesis of product molecules
  • FIG. 2 shows mass spectra for the following Example 1, in which a gas containing various concentrations of CO and H 2 was conducted onto a Pd (100) monocrystal surface and product molecules were synthesized by means of shaped ultrashort laser pulses.
  • Figure 1 shows schematically an arrangement for carrying out the method according to the invention for the synthesis of product molecules from a gas containing CO and H 2 on a surface by means of shaped ultrashort laser pulses.
  • a laser 1 supplies laser pulses 2 whose spectral width enables the generation of laser pulses in the femtosecond range.
  • the laser pulses 2 are optionally amplified (not shown) and strike as unformed laser pulses 3 on a first grid 4, which decomposes the unshaped laser pulses into their spectral components, which meet as divergent beams 6 on a first lens 5.
  • the first lens 5 focuses the divergent beams 6 into a parallel beam 7.
  • a liquid crystal display (LCD) 8 causes a transit time difference of the various spectral components.
  • a second lens 9 focuses the emerging from the liquid crystal display 8 beam 10, which is superimposed by a second grating 1 1 to laser pulses 12.
  • the pulse shaper 14 of this arrangement thus comprises the two gratings 4, 11, the two lenses 5, 9 and the liquid crystal display 8.
  • the ultrashort laser pulses 13 thus formed are directed onto a surface 15 optionally located in a vacuum chamber (not shown) ,
  • the educt molecules CO and H 2 are mixed in a certain ratio of mass flows.
  • the mixture 18 is passed to the surface 15 via a nozzle 19 and a skimmer 20.
  • gas 21 reactants are adsorbed on the surface 15.
  • the shaped laser pulse 13 striking the surface 15 provides the energy to synthesize product molecules 22 from the adsorbed educts.
  • the ionized product molecules 22 are accelerated into a time-of-flight mass spectrometer 23.
  • the ions 27 generate a signal in a detector 24 after times of flight by the time of flight mass spectrometer 23, which depend directly on their mass.
  • These measured signals 25 are transmitted to a computer 28 which is used to optimize the Pulse shape of the shaped laser pulses 13 by means of an optimization algorithm generates a modified pulse shape.
  • the computer 28 then controls the liquid crystal display 8 via the connection 26, so that the pulse shaper 14 forms laser pulses with the generated changed pulse shape, which are used for the synthesis of product molecules on the surface 15.
  • FIG. 1 A construction as shown in FIG. 1 was used.
  • Laser pulses were amplified by means of a titanium sapphire regenerative femtosecond amplifier, the amplified unshaped laser pulses having a pulse duration of 80 fs, pulse energies of up to 1 mJ at a central wavelength of 800 nm and a repetition rate of 1 kHz.
  • a 128-pixel LCD pulse shaper was used to alter the spectral phase of the laser pulses while leaving their spectrum unchanged.
  • the laser beam (shaped laser pulses) was passed through a lens with a focal length of 40 cm into a main vacuum chamber (pressure without gas flow about 10 "6 mbar) onto a Pd (100) single crystal surface (temperature of the crystal 290 K) at an angle of approx
  • the intensity of the laser beam was about 10 12 W / cm 2.
  • the beam was reflected by the surface and left the main vacuum chamber.
  • the two gases H 2 and CO were obtained with a purity of at least 99.999% (from Messer-Griesheim, Germany) or at least 99.997% (from Tyczka, Germany).
  • Two mass flow controllers (from Advanced Energy, Germany) dosed the gas volumes that were fed into the system via two gas lines.
  • the two gas lines were combined in front of a nozzle and the gas mixture passed through the nozzle in a secondary vacuum chamber, where it met with a skimmer and was passed from there as a gas stream in the main vacuum chamber.
  • the Pd (10 O) single crystal was oriented at an angle of about 5 ° to the molecular stream, so that the gas not only grazed it, but hit it.
  • Perpendicular to the gas stream and nearly parallel to the surface normal was a time-of-flight mass spectrometer, with an electrode system for accelerating ions formed as the laser beam interacted with the surface and the adsorbed educts.
  • An optimization of the pulse shape of the shaped ultrashort laser pulses was carried out by means of an evolutionary algorithm. For this purpose, a 1: 1 mixture of the two gases CO and H 2 was passed onto the Pd surface. It should be investigated whether it is possible with the help of the evolutionary algorithm to find a pulse shape that influences the formation of C-H bonds. The goal of the optimization experiment was to maximize the formation of CH + in relation to C + .
  • a pulse shape of the shaped laser pulses was found by means of the evolutionary algorithm, which achieved an increase in the relative yield of about 50% compared to an unshaped femtosecond laser pulse. At the same time, the CH 2 + / C + ratio was increased by about the same value.
  • the H 2 O + yield was integrated into the fitness function used by the evolutionary algorithm.
  • the optimization experiment was carried out with the chosen goal of maximizing the ratio CH + / H 2 O + .
  • the H 2 O + peak could be reduced by about 50% relative to the C + peak.
  • the H 2 O + peak was larger than the CH + peak. This ratio could be reversed by the optimized shaped laser pulse.
  • the CO + and HCO + peak intensities were increased whereas CH + and CH 2 + did not change much relative to C + . In this experiment as well, it was not possible to reduce the H 2 O + signal relative to the other peaks by changing the intensity of an unshaped laser pulse.

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Abstract

The invention relates to a process for the synthesis of product molecules, in which ultrashort laser pulses which have been shaped by means of a pulse shaper are produced and a gas containing starting molecules is directed onto a surface on which the starting molecules are at least partly adsorbed, wherein the shaped ultrashort laser pulses are directed onto the surface in order to control a reaction for the synthesis of the product molecules from starting materials adsorbed on the surface.

Description

Verfahren zur Synthese von ProduktmolekülenProcess for the synthesis of product molecules
Beschreibungdescription
Die Erfindung bezieht sich auf ein Verfahren zur Synthese von Produktmolekülen, mit dem der Ablauf von chemischen Reaktionen gezielt gesteuert werden kann.The invention relates to a process for the synthesis of product molecules, with which the course of chemical reactions can be controlled in a targeted manner.
Die gezielte Steuerung von chemischen Reaktionen auf einer molekularen Ebene ist ein alter Traum der Chemie. Die konventionellen makroskopischen Steuerparameter der Chemie wie Temperatur, Konzentration oder Druck erlauben keinen direkten Zugriff auf den quantenmechanischen Reaktionsverlauf. In den letzten Jahren wurden viele neue Erkenntnisse im Bereich der Quantenkontrolle gewonnen, bei der speziell gestaltete Lichtfelder zum Einsatz kommen, mit deren Hilfe effizient und selektiv bestimmte Reaktionskanäle ausgewählt werden können. Eine experimentelle Technik beruht auf der Manipulation von Femtosekunden-Laserpulsen mittels eines Pulsformers. Diese Technik ist beispielsweise in dem Übersichtsartikel von T. Brixner, G. Gerber: "Quantum Control of Gas-Phase and Liquid-Phase Femtochemistry", CHEMPHYSCHEM 2003, 4, 418 bis 438 beschrieben. Ausgangspunkt ist ein Laserpuls von einigen Fem- tosekunden Dauer (üblicherweise 10 bis 150 fs), der durch ein kommerzielles Lasersystem erzeugt werden kann. Mittels eines sogenannten Pulsformers wird dieser Laserpuls in einen "geformten" Laserpuls überführt, wobei die Formung die Phasen und/oder Amplituden der kohärenten spektralen Bestandteile betrifft, die nicht mehr einheitlich sein müssen, sondern moduliert werden können und so auf den zu optimierenden Reaktionsablauf angepasst sind.Targeted control of chemical reactions on a molecular level is an old dream of chemistry. The conventional macroscopic control parameters of chemistry such as temperature, concentration or pressure do not allow direct access to the quantum-mechanical reaction process. In recent years, many new findings in the field of quantum control have been gained, using specially designed light fields, which can be used to efficiently and selectively select specific reaction channels. An experimental technique relies on the manipulation of femtosecond laser pulses by means of a pulse shaper. This technique is described, for example, in the review article by T. Brixner, G. Gerber: "Quantum Control of Gas-Phase and Liquid-Phase Femtochemistry", CHEMPHYSCHEM 2003, 4, 418-438. The starting point is a laser pulse of a few femtoseconds duration (usually 10 to 150 fs), which can be generated by a commercial laser system. By means of a so-called pulse shaper, this laser pulse is converted into a "shaped" laser pulse, wherein the shaping relates to the phases and / or amplitudes of the coherent spectral components, which need not be uniform, but can be modulated and are adapted to the reaction sequence to be optimized ,
Solche Verfahren wurden bisher hauptsächlich erfolgreich auf dissoziative Reaktionen in der Gasphase angewendet. Aufgabe der vorliegenden Erfindung ist es, die Nachteile des Standes der Technik zu vermeiden und insbesondere eine selektive Bildung von Molekülbindungen mit geformten ultrakurzen Laserpulsen zu ermöglichen.Such methods have been used mainly successfully for dissociative reactions in the gas phase. The object of the present invention is to avoid the disadvantages of the prior art and in particular to enable a selective formation of molecular bonds with shaped ultrashort laser pulses.
Diese Aufgabe wird erfindungsgemäß gelöst durch ein Verfahren zur Synthese von Produktmolekülen, wobei mit Hilfe eines Pulsformers geformte ultrakurze Laserpulse erzeugt werden und ein Gas, das Eduktmoleküle enthält, auf eine Oberfläche geleitet wird, auf der die Eduktmoleküle zumindest teilweise adsorbiert werden, wobei die geformten ultrakurzen Laserpulse auf die Oberfläche gelenkt werden, um einen Reaktionsverlauf zur Synthese der Produktmoleküle aus auf der Oberfläche adsorbierten Edukten zu steuern. Dabei sind die Produktmoleküle Moleküle, deren Ausbeute gezielt durch die geformten Laserpulse beeinflusst werden kann. Sie entstehen durch chemische Reaktionen von Edukten auf der Oberfläche unter dem Einfluss der Laserpulse.This object is achieved by a method for the synthesis of product molecules, wherein ultrashort laser pulses formed with the aid of a pulse shaper are generated and a gas containing educt molecules is passed onto a surface on which the educt molecules are at least partially adsorbed, wherein the ultrashort formed Laser pulses are directed to the surface to control a reaction course for the synthesis of the product molecules from adsorbed on the surface of educts. The product molecules are molecules whose yield can be specifically influenced by the shaped laser pulses. They are caused by chemical reactions of educts on the surface under the influence of laser pulses.
Ultrakurze Laserpulse im Zusammenhang mit dem erfindungsgemäßen Verfahren sind Laserpulse, deren (nach dem Zeit-Bandbreite-Produkt kürzestmögliche) Dauer im Bereich von einer Attosekunde bis 1 Nanosekunde, bevorzugt im Bereich von 1 Femtose- kunde bis 10 Picosekunden liegt, besonders bevorzugt im Bereich von 5 bis 200 Fem- tosekunden. Solche ultrakurzen Laserpulse werden insbesondere durch kommerzielle Femtosekunden-Laser bereitgestellt.Ultrashort laser pulses in connection with the method according to the invention are laser pulses whose duration (as short as possible according to the time-bandwidth product) is in the range of one attosecond to 1 nanosecond, preferably in the range of 1 femtosecond to 10 picoseconds, particularly preferably in the range of 5 to 200 femtoseconds. Such ultrashort laser pulses are provided in particular by commercial femtosecond lasers.
Synthese bedeutet im Zusammenhang mit der Erfindung die Herstellung von Produktmolekülen, bei der neue Molekülbindungen entstehen und bei der die Eduktmoleküle oder die Edukte nicht nur in ihre Bestandteile zerlegt werden. Ferner erfolgt die Syn- these der Produktmoleküle bei der vorliegenden Erfindung vorzugsweise durch multimolekulare Reaktionen, insbesondere durch bimolekulare Reaktionen.Synthesis in connection with the invention means the production of product molecules, in which new molecular bonds are formed and in which the educt molecules or the educts are not only broken down into their constituents. Furthermore, the synthesis of the product molecules in the present invention is preferably carried out by multimolecular reactions, in particular by bimolecular reactions.
Erfindungsgemäß wird ein Gas, das die Eduktmoleküle enthält, auf die Oberfläche geleitet, auf der sie zumindest teilweise adsorbiert werden. Zum Steuern eines Reakti- onsverlaufs zur Synthese der Produktmoleküle aus auf der Oberfläche adsorbierten Edukten werden die geformten ultrakurzen Laserpulse auf die Oberfläche gelenkt. Die auf der Oberfläche adsorbierten Edukte können dabei Eduktmolekülen aus dem auf die Oberfläche geleiteten Gas entsprechen oder daraus entstandene kleinere (dissoziati- ver Prozess) oder größere (Aggregation) Moleküle oder Atome sein.According to the invention, a gas containing the educt molecules is passed to the surface on which they are at least partially adsorbed. To control a reaction course for the synthesis of the product molecules from educts adsorbed on the surface, the shaped ultrashort laser pulses are directed onto the surface. The educts adsorbed on the surface can thereby correspond to educt molecules from the gas conducted onto the surface or be smaller (dissociation process) or larger (aggregation) molecules or atoms resulting therefrom.
Vorzugsweise sind die geformten ultrakurzen Laserpulse für das erfindungsgemäße Verfahren so geformt, dass die Reaktionsausbeute der Produktmoleküle maximiert ist. Die geformten ultrakurzen Laserpulse können jedoch auch so geformt sein, dass die Reaktionsausbeute eines von den zu synthetisierenden Produktmolekülen abweichen- den Produktes minimiert ist.Preferably, the shaped ultrashort laser pulses for the process of the present invention are shaped so that the reaction yield of the product molecules is maximized. However, the shaped ultrashort laser pulses can also be shaped so that the reaction yield of a product deviating from the product molecules to be synthesized is minimized.
Das erfindungsgemäße Verfahren zur Synthese von Produktmolekülen läuft vorzugsweise ab, indem ein kontinuierlicher Massenstrom an Gas mit den Eduktmolekülen auf die Oberfläche geleitet wird und geformte ultrakurze Laserpulse mit einer bestimmten Repetitionsrate auf die Oberfläche gelenkt werden.The process according to the invention for the synthesis of product molecules preferably proceeds by passing a continuous mass flow of gas with the educt molecules onto the surface and directing shaped ultrashort laser pulses onto the surface at a specific repetition rate.
Die Oberfläche dient bei der vorliegenden Erfindung zum Adsorbieren der Edukte und muss daher eine Affinität zu den Eduktmolekülen im Gas aufweisen. Die Oberfläche sollte die Eduktmoleküle oder Edukte mindestens physisorbieren und sie gegebenen- falls sogar chemisorbieren. Bei der Physisorption verbleiben die adsorbierten Eduktmo- leküle in ihrem ursprünglichen chemischen Zustand. Bei der Chemisorption hingegen bilden die Adsorbate eine chemische Bindung mit der Oberfläche. Dabei kann das Adsorbat an der Oberfläche dissoziieren. Die Verwendung der Oberfläche bietet u. a. den Vorteil, dass eine relativ hohe Dichte der Eduktsubstanzen erreicht wird. Dadurch er- geben sich eine höhere Stoßrate und höhere Ausbeuten. In der Gasphase würde die Wahrscheinlichkeit, dass sich mehrere Teilchen treffen, deutlich zu niedrig sein. Ferner kann die Oberfläche z.B. als Katalysator für die Dissoziation oder Aggregation von E- duktmolekülen wirken oder es wird die spezielle Natur des (z.B. metallischen) Trägers ausgenutzt, wie beispielsweise in M. Bonn et al.,:"Phonon- Versus Electron-Mediated Desorption and Oxidation of CO on Ru(OOOI )", SCIENCE 1999, 285, 1042 bis 1045, beschrieben.The surface serves in the present invention for adsorbing the educts and therefore must have an affinity for the educt molecules in the gas. The surface should at least physisorb the educt molecules or educts and if necessary even chemisorb them. In physisorption, the adsorbed Eduktmo- remain molecules in their original chemical state. In the case of chemisorption, however, the adsorbates form a chemical bond with the surface. The adsorbate can dissociate on the surface. The use of the surface offers, inter alia, the advantage that a relatively high density of the educt substances is achieved. This results in a higher burst rate and higher yields. In the gas phase, the likelihood of multiple particles colliding would be far too low. Furthermore, the surface may act, for example, as a catalyst for the dissociation or aggregation of eu duktmolekülen or the special nature of the (eg metallic) carrier is exploited, as for example in M. Bonn et al.,: "Phonon-Versus Electron-Mediated Desorption and Oxidation of CO on Ru (OOOI) ", SCIENCE 1999, 285, 1042-1045.
Die geformten ultrakurzen Laserpulse wechselwirken bei dem erfindungsgemäßen Verfahren mit der Oberfläche und den adsorbierten Edukten zur Synthese der Pro- duktmoleküle. Gemäß einer bevorzugten Ausführungsform der vorliegenden Erfindung übernimmt die Oberfläche zusätzlich zu ihrer Funktion als Sorbens auch noch die Funktion eines Katalysators, der die Synthese der Produktmoleküle katalysiert.The shaped ultrashort laser pulses interact in the method according to the invention with the surface and the adsorbed educts for the synthesis of the product molecules. According to a preferred embodiment of the present invention, in addition to its function as a sorbent, the surface also performs the function of a catalyst which catalyzes the synthesis of the product molecules.
Gemäß einer bevorzugten Ausführungsform der vorliegenden Erfindung formt der PuIs- former spektrale Anteile von Laserpulsen in Bezug auf Intensität (Amplitude) und Phase. Dabei werden die ungeformten Laserpulse, die beispielsweise ein kommerzieller Femtosekunden-Laser emittiert und bei denen alle spektralen Anteile zur selben Zeit auftreten, durch den Pulsformer in geformte Laserpulse, die zu unterschiedlichen Zeiten variabel einstellbare Anteile der verschiedenen Spektralfarben aufweisen können, überführt. Durch den Pulsformer ist auch die Dauer eines Laserpulses variierbar, sofern dessen spektrale Breite die Erzeugung eines Laserpulses in dem gewünschten Zeitbereich ermöglicht. Die relativen Farbanteile (Intensität) und deren zeitliche Anordnung (Phase) in dem geformten ultrakurzen Laserpuls beeinflussen direkt die Ausbeute bei der Synthese der Produktmoleküle aus auf der Oberfläche adsorbierten Edukten.According to a preferred embodiment of the present invention, the pulse former shapes spectral components of laser pulses in terms of intensity (amplitude) and phase. In this case, the unshaped laser pulses, which emits, for example, a commercial femtosecond laser and in which all the spectral components occur at the same time, are converted by the pulse shaper into shaped laser pulses, which can have variably adjustable components of the different spectral colors at different times. By the pulse shaper, the duration of a laser pulse is variable, provided that its spectral width allows the generation of a laser pulse in the desired time range. The relative color components (intensity) and their temporal arrangement (phase) in the shaped ultrashort laser pulse directly influence the yield in the synthesis of the product molecules from educts adsorbed on the surface.
Gemäß einer Ausführungsform der vorliegenden Erfindung formt der Pulsformer spektrale Anteile von Laserpulsen in Bezug auf Polarisation. Damit ist ein weiterer Parameter zur Optimierung der Laserpulsform gegeben, durch den die Ausbeute an Produktmolekülen noch erhöht werden kann. Dabei steuert der Pulsformer den Polarisations- zustand von Licht auf einer ultrakurzen Zeitskala. Ein solcher Polarisationspulsformer manipuliert vorzugsweise die vorübergehende Intensität, die momentane Frequenz, den Grad der Elliptizität und die Orientierung der elliptischen Hauptachsen in jedem einzelnen ultrakurzen Laserpuls. Eine bevorzugte Ausführungsform des erfindungsgemäßen Verfahrens besteht darin, dass während der Synthese eine Optimierung der geformten ultrakurzen Laserpulse durch Messen mittels eines Detektors, welche Produkte mit welchen Ausbeuten bei der Synthese der Produktmoleküle entstehen, Generieren einer geänderten Pulsform mit- tels eines Rechners durch einen Optimierungsalgorithmus und Ansteuern des Pulsformers, so dass die geformten ultrakurzen Laserpulse mit der geänderten Pulsform erzeugt werden, erfolgt. Dies hat den Vorteil, dass zur Optimierung der Produktmolekülsynthese kein Vorwissen über die Eduktmoleküle/Edukte, die Oberfläche oder den Ablauf der chemischen Reaktion erforderlich ist. Der Rechner (zum Beispiel ein Personal Computer) übernimmt die Steuerung des Pulsformers und kann zum Beispiel die Reaktionsausbeute optimieren. Das iterative Verbessern der Laserpulsform läuft dabei wie folgt ab. Es werden ultrakurze Laserpulse auf die Oberfläche gelenkt, um eine Reaktion zur Synthese der Produktmoleküle auszulösen. Mit Hilfe eines Detektors wird gemessen, welche Produkte dabei mit welcher Ausbeute erzeugt werden. Als Detektor kann jeder dem Fachmann bekannte, zum Nachweis der Produkte geeignete Detektor verwendet werden. Vorzugsweise ist der Detektor ein Detektor, der auf mindestens einer der zeitaufgelösten Nachweismethoden ausgewählt aus der Gruppe Flugzeitmassenspektroskopie, Photoelektronenspektroskopie, Emissionsspektroskopie und zweidimensionale Spektroskopie und Vierwellenmischen beruht.According to an embodiment of the present invention, the pulse shaper forms spectral components of laser pulses with respect to polarization. Thus, another parameter for optimizing the laser pulse shape is given, by which the yield of product molecules can be increased. The pulse shaper controls the polarization state of light on an ultrashort time scale. Such a polarization pulse shaper preferably manipulates the transient intensity, the instantaneous frequency, the degree of ellipticity, and the orientation of the major elliptical axes in each individual ultrashort laser pulse. A preferred embodiment of the method according to the invention is that during the synthesis, an optimization of the shaped ultrashort laser pulses by measuring by means of a detector, which products with what yields in the synthesis of the product molecules, generating a modified pulse shape by means of a computer by an optimization algorithm and Driving the pulse shaper, so that the shaped ultrashort laser pulses are generated with the changed pulse shape takes place. This has the advantage that for the optimization of the product molecule synthesis no prior knowledge about the educt molecules / reactants, the surface or the course of the chemical reaction is required. The computer (for example a personal computer) takes over the control of the pulse shaper and can, for example, optimize the reaction yield. The iterative improvement of the laser pulse form proceeds as follows. Ultrashort laser pulses are directed to the surface to initiate a reaction to synthesize the product molecules. A detector is used to measure which products are produced at what yield. Any suitable detector known to the person skilled in the art and suitable for detecting the products can be used as the detector. Preferably, the detector is a detector based on at least one of the time-resolved detection methods selected from the group of time-of-flight mass spectroscopy, photoelectron spectroscopy, emission spectroscopy, and two-dimensional spectroscopy and four-wave mixing.
Der Rechner verarbeitet die von dem Detektor ermittelte Information über die Ausbeuten der verschiedenen Produkte. Durch den Optimierungsalgorithmus werden verbesserte Pulsformen der Laserpulse generiert, die wiederum von dem Pulsformer erzeugt und zur Synthese der Produktmoleküle auf die Oberfläche gelenkt werden. Dieses Op- timierungsverfahren wird wiederholt, bis die Synthese der Produktmoleküle zum Beispiel auf ein Maximum der erwünschten Produktmolekülausbeute (Selektivität) relativ zur Ausbeute eines unerwünschten Produktes oder auf ein Minimum einer relativen Ausbeute (Selektivität) eines solchen unerwünschten Produktes optimiert ist.The computer processes the information determined by the detector on the yields of the various products. The optimization algorithm generates improved pulse shapes of the laser pulses, which in turn are generated by the pulse shaper and directed to the surface for synthesis of the product molecules. This optimization procedure is repeated until synthesis of the product molecules is optimized, for example, to a maximum of the desired product molecule yield (selectivity) relative to the yield of an undesired product or to a minimum of relative yield (selectivity) of such undesired product.
Als Optimierungsalgorithmus dient dabei vorzugsweise ein evolutionärer Algorithmus. Dieser Computeralgorithmus ist ein selbstlernendes Verfahren, das der biologischen Evolution nachempfunden ist. Nach Darwins Prinzip "Survival of the fittest" (der Beste überlebt) werden Laserpulse, die das Optimierungsziel besonders gut erfüllen, ausgewählt und durch Kombination mit ähnlich erfolgreichen Phaseneinstellungen "fortge- pflanzt". Einige der hierdurch erzeugten "Nachkommen" sind wiederum besser geeignet als ihre "Vorfahren" (ihnen wird eine höhere "Fitness" zugeordnet), und sie werden erneut zur Reproduktion ausgewählt. Wenn dieser Vorgang der Evolution für genügend viele Generationen durchschritten wird, findet sich schließlich ein Laserpuls, der das optimale Reaktionsergebnis hervorbringt. Gemäß einer bevorzugten Ausführungsform der vorliegenden Erfindung werden die Laserpulse durch einen Pulsformer geformt, der auf einer rechnergesteuerten Technik beruht, die ein Ansteuern von mindestens einer Einrichtung ausgewählt aus der Gruppe Flüssigkristalldisplay, akusto-optischer Modulator, akusto-optischer Filter, verform- barer Spiegel und Mikrospiegelanordnung umfasst. Das Formen eines Laserpulses mittels eines Pulsformers in Bezug auf spektrale Intensität und Phase, sowie Polarisation beruht üblicherweise darauf, dass der Laserpuls (zum Beispiel mittels eines Gitters oder mittels Prismen) in seine spektralen Anteile aufgespalten wird, daraus ein paralleles Strahlenbündel erzeugt wird, eine als "Phasenschieber" wirkende Einrichtung einen Laufzeitunterschied der spektralen Anteile bewirkt und das Strahlenbündel wieder fo- kussiert und (zum Beispiel durch ein weiteres Gitter) zu einem geformten Laserpuls überlagert wird. Als eine solche als "Phasenschieber" wirkende Einrichtung kann beispielsweise mindestens ein Flüssigkristalldisplay (LCD), ein akusto-optischer Modulator, ein verformbarer Spiegel oder eine Mikrospiegelanordnung dienen, oder auch ein akusto-optischer Filter, für den allerdings keine Aufspaltung der spektralen Komponenten notwendig ist.The optimization algorithm used is preferably an evolutionary algorithm. This computer algorithm is a self-learning process modeled on biological evolution. According to Darwin's principle "Survival of the fittest" (the best survived), laser pulses that particularly fulfill the optimization goal are selected and "propagated" by combination with similarly successful phase settings. Some of the "offspring" produced this way are better suited than their "ancestors" (they are given a higher "fitness"), and they are re-selected for reproduction. If this process of evolution is passed through for enough generations, then finally a laser pulse is found, which produces the optimal reaction result. According to a preferred embodiment of the present invention, the laser pulses are formed by a pulse shaper based on a computer-controlled technique which drives at least one device selected from the group consisting of liquid crystal display, acousto-optic modulator, acousto-optic filter, deformable mirror and Micromirror arrangement comprises. Forming a laser pulse by means of a pulse shaper in terms of spectral intensity and phase, and polarization usually based on the fact that the laser pulse is split (for example by means of a grating or prisms) in its spectral components, from which a parallel beam is generated, as a "Phase shifter" acting causes a transit time difference of the spectral components and the beam is again focused and (for example, by another grid) is superimposed on a shaped laser pulse. For example, at least one liquid crystal display (LCD), an acousto-optical modulator, a deformable mirror or a micromirror arrangement may serve as such a device acting as a "phase shifter," or else an acousto-optic filter, for which, however, no splitting of the spectral components is necessary ,
Die Manipulation der Pulsform mittels Flüssigkristalldisplay erfolgt durch Anlegen von geeigneten elektrischen Spannungen an die einzelnen LCD-Pixel, wodurch die Bre- chungsindizes so gewählt werden können, dass die verschiedenen spektralen Komponenten bei der Ausbreitung durch das LCD relativ zueinander verzögert werden.The manipulation of the pulse shape by means of a liquid crystal display is carried out by applying suitable electrical voltages to the individual LCD pixels, whereby the refractive indices can be chosen such that the different spectral components are delayed relative to one another as they propagate through the LCD.
Der akusto-optische Filter basiert auf einer anderen Methode, bei der das Licht nicht erst in seine spektralen Komponenten aufgespalten werden muss. Vielmehr propagie- ren das Licht und eine akustische Welle durch einen speziellen doppelbrechenden Kristall. Jede spektrale Komponente kann an dem akustischen Gitter an einer bestimmten Position im Kristall z.B. von einem ordentlichen in einen außerordentlichen Strahl gebeugt werden. Der resultierende Puls besteht demnach aus den einzelnen Farbanteilen, die zu unterschiedlichen Zeiten gebeugt wurden, wodurch eine Phasenmodula- tion möglich ist.The acousto-optic filter is based on another method, in which the light does not first have to be split into its spectral components. Rather, the light and an acoustic wave propagate through a special birefringent crystal. Each spectral component may be attached to the acoustic grating at a particular position in the crystal, e.g. be bent from a normal to an extraordinary ray. The resulting pulse therefore consists of the individual color components which have been diffracted at different times, whereby a phase modulation is possible.
Gemäß einer bevorzugten Ausführungsform der vorliegenden Erfindung wird das die Eduktmoleküle enthaltende Gas auf eine Oberfläche geleitet, die eine metallische Oberfläche oder eine Metalloxidoberfläche ist und die vorzugsweise mindestens ein Element aus einer der Nebengruppen MIB bis IIB (Übergangsmetalle), besonders bevorzugt aus einer der Gruppen VIIIB, IB und IIB des Periodensystems der Elemente enthält. Bevorzugte Elemente der Gruppen VIIIB, IB und IIB des Periodensystems der Elemente sind dabei Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Cd, Os, Ir, Pt, Au und Hg. In der für das erfindungsgemäße Verfahren verwendeten Oberfläche können die Metalle auch als Legierung vorliegen oder gemäß einer weiteren Ausführungsform wird das die Eduktmoleküle enthaltende Gas auf eine Oberfläche geleitet, die eine Einkristalloberfläche eines Übergangsmetalls ist, zum Beispiel Pd (100), Pt (100) oder Ag (11 1 ). Gemäß einer weiteren bevorzugten Ausführungsform der vorliegenden Erfindung handelt es sich bei der Oberfläche um eine Oberfläche eines technischen Katalysators, zum Beispiel eines technischen Katalysators, der die genannten Elemente geträgert oder ungeträgert, rein, als Legierungen oder als Oxide enthält.According to a preferred embodiment of the present invention, the gas containing the educt molecules is passed onto a surface which is a metallic surface or a metal oxide surface and which preferably at least one element from one of the subgroups MIB to IIB (transition metals), more preferably from one of the groups VIIIB , IB and IIB of the Periodic Table of the Elements. Preferred elements of Groups VIIIB, IB and IIB of the Periodic Table of the Elements are Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ag, Cd, Os, Ir, Pt, Au and Hg. In the for the inventive Surface treatment method, the metals may also be present as an alloy or according to another embodiment, which is the Gas containing educt molecules is passed onto a surface which is a single-crystal surface of a transition metal, for example Pd (100), Pt (100) or Ag (11 1). According to a further preferred embodiment of the present invention, the surface is a surface of a technical catalyst, for example a technical catalyst, which supports said elements supported or unsupported, pure, as alloys or as oxides.
Das Gas, das bei dem erfindungsgemäßen Verfahren auf die Oberfläche geleitet wird, enthält eine oder mehrere Sorten von Eduktmolekülen. Beispielsweise können erfin- dungsgemäß Produktmoleküle durch eine Polymerisationsreaktion aus nur einer Sorte von Eduktmolekülen synthetisiert werden. Vorzugsweise enthält es ein Gemisch aus mindestens zwei Sorten von Eduktmolekülen, wobei ein Verhältnis von Massenströmen der mindestens zwei Sorten von Eduktmolekülen durch eine Regeleinrichtung geregelt werden kann. Das Verhältnis der Massenströme hat, ebenso wie die Pulsform der geformten Laserpulse, einen Einfluss auf die Ausbeute der Produktmoleküle bei der Durchführung des erfindungsgemäßen Verfahrens. Eine Regeleinrichtung kann daher die Massenströme der mindestens zwei Sorten von Eduktmolekülen so regeln, dass eine bestimmte maximale Ausbeute der Produktmoleküle erreicht wird.The gas which is passed onto the surface in the method according to the invention contains one or more types of educt molecules. For example, according to the invention, product molecules can be synthesized by a polymerization reaction from only one kind of starting material molecules. Preferably, it contains a mixture of at least two types of educt molecules, wherein a ratio of mass flows of the at least two types of educt molecules can be regulated by a control device. The ratio of the mass flows, as well as the pulse shape of the shaped laser pulses, has an influence on the yield of the product molecules in carrying out the method according to the invention. A control device can therefore regulate the mass flows of the at least two types of educt molecules in such a way that a certain maximum yield of the product molecules is achieved.
Vorzugsweise wird bei dem erfindungsgemäßen Verfahren ein Gas auf die Oberfläche geleitet, das mindestens eine Sorte von Eduktmolekülen ausgewählt aus der Gruppe Aceton, Acetylen, Ameisensäure, Ammoniak, Arsin, Blausäure, Bortrichlorid, Bortrifluo- rid, Bromethen, Brommethan, Bromwasserstoff, 1.3-Butadien, Butan, 1 -Buten, 1-Butin, Chlor, Chlordifluormethan, Chlorethen, Chlormethan, Chlorwasserstoff, cis-2-Buten, Deuterium, Dichlorsilan, Diethylether, Difluormethan, Dimethylamin, Dimethylether, 2,2- Dimethylpropan, Disilan, Distickstoffmonoxid, Stickoxydul, Ethan, Ethen, Ethylenoxid, Fluormethan, Formaldehyd, Hexafluorethan, Isobutan, Isobuten, Kohlendioxid, Koh- lenmonoxid, Methan, Methanol, Methylamin, Octafluorcyclobutan, Octafluorpropan, Phosphin, Propan, Propen, 1 -Propin, Propylenoxid, Sauerstoff, Schwefeldioxid, Schwe- felhexafluorid, Schwefelwasserstoff, Silan, Siliciumtetrafluorid, Stickstoff, Stickstoffdi- oxid/Distickstofftetroxid, Stickstoffmonoxid, Stickstofftrifluorid, Tetrafluormethan, trans- 2-Buten, Trifluormethan, Trimethylamin und Wasserstoff enthält. Besonders bevorzugt enthält das Gas als Eduktmoleküle H2 und CO. Das erfindungsgemäße Verfahren kann zur Synthese zum Beispiel von Formaldehyd oder Methanol verwendet werden.Preferably, in the method according to the invention, a gas is passed to the surface, the at least one kind of Eduktmolekülen selected from the group acetone, acetylene, formic acid, ammonia, arsine, hydrocyanic acid, boron trichloride, boron trifluoride, bromothene, bromomethane, hydrogen bromide, 1.3-butadiene , Butane, 1-butene, 1-butyne, chlorine, chlorodifluoromethane, chloroethene, chloromethane, hydrogen chloride, cis-2-butene, deuterium, dichlorosilane, diethyl ether, difluoromethane, dimethylamine, dimethyl ether, 2,2-dimethylpropane, disilane, nitrous oxide, nitrous oxide , Ethane, ethene, ethylene oxide, fluoromethane, formaldehyde, hexafluoroethane, isobutane, isobutene, carbon dioxide, carbon monoxide, methane, methanol, methylamine, octafluorocyclobutane, octafluoropropane, phosphine, propane, propene, propotine, propylene oxide, oxygen, sulfur dioxide, sulfur felhexafluoride, hydrogen sulfide, silane, silicon tetrafluoride, nitrogen, nitrogen dioxide / dinitrogen tetroxide, nitric oxide, nitrogen trifluoro chloride, tetrafluoromethane, trans-2-butene, trifluoromethane, trimethylamine and hydrogen. The gas particularly preferably contains H 2 and CO as starting material molecules. The process according to the invention can be used for the synthesis of, for example, formaldehyde or methanol.
Gemäß einer Ausführungsform der vorliegenden Erfindung wird das die Eduktmoleküle enthaltende Gas in einer Vakuumkammer auf die Oberfläche geleitet. In der Vakuumkammer herrscht vorzugsweise ein Vakuum < 10"3 mbar, insbesondere < 10"4 mbar, wenn das Gas der Oberfläche zugeführt wird. Die vorliegende Erfindung wird nachstehend anhand der Zeichnung näher erläutert.According to one embodiment of the present invention, the gas containing the educt molecules is conducted onto the surface in a vacuum chamber. In the vacuum chamber there is preferably a vacuum <10 "3 mbar, in particular <10 " 4 mbar, when the gas is supplied to the surface. The present invention is explained below with reference to the drawing.
Es zeigtIt shows
Figur 1 schematisch eine Anordnung zur Durchführung des erfindungsgemäßen Verfahrens zur Synthese von Produktmolekülen undFigure 1 shows schematically an arrangement for carrying out the method according to the invention for the synthesis of product molecules and
Figur 2 Massenspektren zu nachfolgendem Beispiel 1 , in dem ein in verschiedenen Konzentrationen CO und H2 enthaltendes Gas auf eine Pd (100)- Einkristalloberfläche geleitet wurde und Produktmoleküle mittels geformter ultrakurzer Laserpulse synthetisiert wurden.FIG. 2 shows mass spectra for the following Example 1, in which a gas containing various concentrations of CO and H 2 was conducted onto a Pd (100) monocrystal surface and product molecules were synthesized by means of shaped ultrashort laser pulses.
Figur 1 zeigt schematisch eine Anordnung zur Durchführung des erfindungsgemäßen Verfahrens zur Synthese von Produktmolekülen aus einem CO und H2 enthaltenden Gas auf einer Oberfläche mittels geformter ultrakurzer Laserpulse.Figure 1 shows schematically an arrangement for carrying out the method according to the invention for the synthesis of product molecules from a gas containing CO and H 2 on a surface by means of shaped ultrashort laser pulses.
Ein Laser 1 liefert Laserpulse 2, deren spektrale Breite die Erzeugung von Laserpulsen im Femtosekundenbereich ermöglicht. Die Laserpulse 2 werden gegebenenfalls verstärkt (nicht dargestellt) und treffen als ungeformte Laserpulse 3 auf ein erstes Gitter 4, das die ungeformten Laserpulse in ihre spektralen Anteile zerlegt, die als divergente Strahlen 6 auf eine erste Linse 5 treffen. Die erste Linse 5 bündelt die divergenten Strahlen 6 in ein paralleles Strahlenbündel 7. Ein Flüssigkristalldisplay (LCD) 8 bewirkt einen Laufzeitunterschied der verschiedenen spektralen Anteile. Eine zweite Linse 9 fokussiert das aus dem Flüssigkristalldisplay 8 austretende Strahlenbündel 10, das von einem zweiten Gitter 1 1 zu Laserpulsen 12 überlagert wird. Der Pulsformer 14 dieser Anordnung umfasst folglich die zwei Gitter 4, 1 1 , die zwei Linsen 5, 9 und das Flüssigkristalldisplay 8. Die so geformten ultrakurzen Laserpulse 13 werden auf eine Oberfläche 15 gelenkt, die sich gegebenenfalls in einer (nicht dargestellten) Vakuumkammer befindet.A laser 1 supplies laser pulses 2 whose spectral width enables the generation of laser pulses in the femtosecond range. The laser pulses 2 are optionally amplified (not shown) and strike as unformed laser pulses 3 on a first grid 4, which decomposes the unshaped laser pulses into their spectral components, which meet as divergent beams 6 on a first lens 5. The first lens 5 focuses the divergent beams 6 into a parallel beam 7. A liquid crystal display (LCD) 8 causes a transit time difference of the various spectral components. A second lens 9 focuses the emerging from the liquid crystal display 8 beam 10, which is superimposed by a second grating 1 1 to laser pulses 12. The pulse shaper 14 of this arrangement thus comprises the two gratings 4, 11, the two lenses 5, 9 and the liquid crystal display 8. The ultrashort laser pulses 13 thus formed are directed onto a surface 15 optionally located in a vacuum chamber (not shown) ,
Aus einem CO-Reservoir 16 und einem H2-Reservoir 17 werden die Eduktmoleküle CO und H2 in einem bestimmten Verhältnis von Massenströmen gemischt. Das Gemisch 18 wird über eine Düse 19 und einen Skimmer 20 auf die Oberfläche 15 geleitet. Aus dem auf die Oberfläche 15 treffenden Gas 21 werden Edukte auf der Oberfläche 15 adsorbiert. Der auf die Oberfläche 15 treffende geformte Laserpuls 13 liefert die Energie zur Synthese von Produktmolekülen 22 aus den adsorbierten Edukten. Die ionisierten Produktmoleküle 22 werden in ein Flugzeitmassenspektrometer 23 beschleunigt. Die Ionen 27 generieren ein Signal in einem Detektor 24 nach Flugzeiten durch das Flugzeitmassenspektrometer 23, die direkt von ihrer Masse abhängen. Diese gemes- senen Signale 25 werden an einen Rechner 28 übertragen, der zur Optimierung der Pulsform der geformten Laserpulse 13 mittels eines Optimierungsalgorithmus eine geänderte Pulsform generiert. Der Rechner 28 steuert dann über die Verbindung 26 das Flüssigkristalldisplay 8 an, so dass der Pulsformer 14 Laserpulse mit der generierten geänderten Pulsform formt, die zur Synthese von Produktmolekülen auf der Oberfläche 15 eingesetzt werden.From a CO reservoir 16 and a H 2 reservoir 17, the educt molecules CO and H 2 are mixed in a certain ratio of mass flows. The mixture 18 is passed to the surface 15 via a nozzle 19 and a skimmer 20. From the impact on the surface 15 gas 21 reactants are adsorbed on the surface 15. The shaped laser pulse 13 striking the surface 15 provides the energy to synthesize product molecules 22 from the adsorbed educts. The ionized product molecules 22 are accelerated into a time-of-flight mass spectrometer 23. The ions 27 generate a signal in a detector 24 after times of flight by the time of flight mass spectrometer 23, which depend directly on their mass. These measured signals 25 are transmitted to a computer 28 which is used to optimize the Pulse shape of the shaped laser pulses 13 by means of an optimization algorithm generates a modified pulse shape. The computer 28 then controls the liquid crystal display 8 via the connection 26, so that the pulse shaper 14 forms laser pulses with the generated changed pulse shape, which are used for the synthesis of product molecules on the surface 15.
Beispiel 1example 1
Es wurde ein Aufbau wie in Figur 1 dargestellt verwendet. Mittels eines Titansaphir regenerativen Femtosekundenverstärkers wurden Laserpulse verstärkt, wobei die verstärkten ungeformten Laserpulse eine Pulsdauer von 80 fs, Pulsenergien von bis zu 1 mJ bei einer zentralen Wellenlänge von 800 nm und eine Repititionsrate von 1 kHz aufwiesen. Ein LCD-Pulsformer mit 128 Pixeln wurde eingesetzt, um die spektrale Phase der Laserpulse zu verändern, während ihr Spektrum unverändert blieb. Der Laserstrahl (geformte Laserpulse) wurde durch eine Linse mit einer Brennweite von 40 cm in eine Hauptvakuumkammer (Druck ohne Gasstrom ca. 10"6 mbar) auf eine Pd (IOO)-Einkristalloberfläche (Temperatur des Kristalls 290 K) unter einem Winkel von ca. 15 ° fokussiert. Die Intensität des Laserstrahls war ca. 1012 W/cm2. Der Strahl wurde durch die Oberfläche reflektiert und verließ die Hauptvakuumkammer.A construction as shown in FIG. 1 was used. Laser pulses were amplified by means of a titanium sapphire regenerative femtosecond amplifier, the amplified unshaped laser pulses having a pulse duration of 80 fs, pulse energies of up to 1 mJ at a central wavelength of 800 nm and a repetition rate of 1 kHz. A 128-pixel LCD pulse shaper was used to alter the spectral phase of the laser pulses while leaving their spectrum unchanged. The laser beam (shaped laser pulses) was passed through a lens with a focal length of 40 cm into a main vacuum chamber (pressure without gas flow about 10 "6 mbar) onto a Pd (100) single crystal surface (temperature of the crystal 290 K) at an angle of approx The intensity of the laser beam was about 10 12 W / cm 2. The beam was reflected by the surface and left the main vacuum chamber.
Die zwei Gase H2 und CO wurden mit einer Reinheit von mindestens 99,999 % (von Messer-Griesheim, Deutschland) beziehungsweise von mindestens 99,997 % (von Tyczka, Deutschland) bezogen. Zwei Massenflussregler (von Advanced Energy, Deutschland) dosierten die Gasmengen, die über zwei Gasleitungen in das System geleitet wurden. Die zwei Gasleitungen wurden vor einer Düse zusammengeführt und das Gasgemisch durch die Düse in eine Nebenvakuumkammer geleitet, wo es auf einen Skimmer traf und von dort aus als Gasstrom in die Hauptvakuumkammer geleitet wurde. Der Pd (I OO)-Einkristall (Durchmesser 10 mm, Dicke 1 mm, von Mateck, Deutschland) wurde in einem Winkel von ca. 5 ° zu dem Molekülstrom ausgerichtet, so dass das Gas ihn nicht nur streifte, sondern darauf auftraf.The two gases H 2 and CO were obtained with a purity of at least 99.999% (from Messer-Griesheim, Germany) or at least 99.997% (from Tyczka, Germany). Two mass flow controllers (from Advanced Energy, Germany) dosed the gas volumes that were fed into the system via two gas lines. The two gas lines were combined in front of a nozzle and the gas mixture passed through the nozzle in a secondary vacuum chamber, where it met with a skimmer and was passed from there as a gas stream in the main vacuum chamber. The Pd (10 O) single crystal (diameter 10 mm, thickness 1 mm, from Mateck, Germany) was oriented at an angle of about 5 ° to the molecular stream, so that the gas not only grazed it, but hit it.
Senkrecht zu dem Gasstrom und nahezu parallel zu der Oberflächennormalen war ein Flugzeitmassenspektrometer angeordnet, mit einem Elektrodensystem zum Beschleu- nigen von Ionen, die entstanden, wenn der Laserstrahl mit der Oberfläche und den adsorbierten Edukten wechselwirkte.Perpendicular to the gas stream and nearly parallel to the surface normal was a time-of-flight mass spectrometer, with an electrode system for accelerating ions formed as the laser beam interacted with the surface and the adsorbed educts.
Erste Ergebnisse des erfindungsgemäßen Verfahrens sind in Figur 2 dargestellt. Auf der Ordinate ist die Intensität I eines mittels eines Detektors am Ende des Flugzeit- massenspektrometers gemessenen lonensignals und auf der Abszisse die Flugzeit t in μs aufgetragen. Es werden die Ergebnisse von 6 Messungen A bis F gezeigt, bei denen der jeweilige Massenfluss der beiden CO- und H2-Eduktmolekülströme wie folgt gewählt wurde:First results of the method according to the invention are shown in FIG. The ordinate indicates the intensity I of an ion signal measured by means of a detector at the end of the time-of-flight mass spectrometer and the abscissa the time of flight t in μs applied. The results of 6 measurements A to F are shown, in which the respective mass flow of the two CO and H 2 -enduct molecule flows was selected as follows:
wobei sccm für Standard ccm/min. steht.where sccm is standard ccm / min. stands.
In Messung A wurde nur H2 und kein CO auf die Oberfläche geleitet. In dem dargestellten Zeitfenster sind keine Signale zu sehen, es wurden jedoch drei große Massen- peaks beobachtet, die H+, H2 + und H3 + zugeordnet werden konnten.In measurement A, only H 2 and no CO were passed to the surface. No signals can be seen in the time window shown, but three large mass peaks were observed which could be assigned to H + , H 2 + and H 3 + .
In Messung B wurde nur CO und kein H2 auf die Oberfläche geleitet. Die drei detektier- ten Massenpeaks liegen bei den Massen 12, 16 und 28 amu, die C+, O+ und CO+ zugeordnet werden können.In measurement B, only CO and no H 2 were passed to the surface. The three detected mass peaks are at masses 12, 16 and 28 amu, which can be assigned to C + , O + and CO + .
Für die Messungen C bis F wurden beide Eduktmolekülsorten CO und H2 der Oberfläche als Gasgemisch zugeführt und es wurden je nach Verhältnis der Massenströme die Ionen C+, CH+, CH2 +, CH3 +, O+, OH+, H2O+, H3O+, CO+, HCO+ und H2CO+ in verschiedenen Intensitäten nachgewiesen. Der Wasserpeak (H2O+) vergrößert sich beispielsweise mit steigendem H2-Massenstrom, wobei der O+-Peak kleiner wird. Durch die Optimierung der Laserpulsformen konnte die Ausbeute von bestimmten Produktmolekülformen noch verbessert werden (nicht dargestellt). Der Nachweis zum Beispiel von CH3 + zeigt, dass 3 Teilchen aufeinander getroffen sein und mit der Oberfläche und dem Laserpuls interagiert haben müssen. Mittels des erfindungsgemäßen Verfahrens wurde folglich erfolgreich eine Synthese von Produktmolekülen erreicht.For the measurements C to F both Eduktmolekülsorten CO and H 2 of the surface were supplied as a gas mixture and depending on the ratio of the mass flows, the ions C + , CH + , CH 2 + , CH 3 + , O + , OH + , H 2 O + , H 3 O + , CO + , HCO + and H 2 CO + detected in different intensities. The water peak (H 2 O + ) increases, for example, with increasing H 2 mass flow, whereby the O + peak becomes smaller. By optimizing the laser pulse shapes, the yield of certain product molecule forms could be improved (not shown). The demonstration of, for example, CH 3 + shows that 3 particles must have met each other and interacted with the surface and the laser pulse. Consequently, a synthesis of product molecules has been successfully achieved by means of the process according to the invention.
Beispiel 2Example 2
Es wurde eine Optimierung der Pulsform der geformten ultrakurzen Laserpulse mittels eines evolutionären Algorithmus durchgeführt. Dazu wurde eine 1 :1 - Mischung der beiden Gase CO und H2 auf die Pd-Oberfläche geleitet. Es sollte untersucht werden, ob es mit Hilfe des evolutionären Algorithmus möglich ist, eine Pulsform zu finden, die die Bildung von C-H-Bindungen beeinflusst. Als Ziel des Optimierungs-Experiments wurde vorgegeben, dass die Bildung von CH+ im Verhältnis zu C+ maximiert werden sollte. Es wurde mittels des evolutionären Algorithmus eine Pulsform der geformten Laserpulse gefunden, durch die eine Erhöhung der relativen Ausbeute um ca. 50% verglichen mit einem ungeformten Femtosekunden-Laserpuls erreicht wurde. Gleichzeitig wurde das CH2 +/C+-Verhältnis um ca. den gleichen Wert erhöht. Ein sehr überraschender Effekt war ferner die auffällige Reduzierung der H2O+-Bildung mit dem optimierten geformten Femtosekunden-Laserpuls. Durch eine Variation der Laserintensität konnte hingegen keine Reduzierung des H2O+-Signals relativ zu den anderen Peaks erreicht werden. Aus diesen experimentellen Daten ergibt sich folglich, dass der ermittelte optimal geformte ultrakurze Laserpuls eine Erhöhung des Signals von Produkten mit C-H-Bindungen verursacht, wohingegen das Signal von H2O+ reduziert wird. Die Ausbeute von CO+, HCO+ und H2CO+ relativ to C+ wurde dabei ebenfalls erhöht.An optimization of the pulse shape of the shaped ultrashort laser pulses was carried out by means of an evolutionary algorithm. For this purpose, a 1: 1 mixture of the two gases CO and H 2 was passed onto the Pd surface. It should be investigated whether it is possible with the help of the evolutionary algorithm to find a pulse shape that influences the formation of C-H bonds. The goal of the optimization experiment was to maximize the formation of CH + in relation to C + . A pulse shape of the shaped laser pulses was found by means of the evolutionary algorithm, which achieved an increase in the relative yield of about 50% compared to an unshaped femtosecond laser pulse. At the same time, the CH 2 + / C + ratio was increased by about the same value. A very surprising effect was also the conspicuous reduction of H 2 O + formation with the optimized shaped femtosecond laser pulse. By varying the laser intensity, however, no reduction of the H 2 O + signal could be achieved relative to the other peaks. From this experimental data, it follows that the determined optimally shaped ultrashort laser pulse causes an increase in the signal of products with CH bonds, whereas the signal of H 2 O + is reduced. The yield of CO + , HCO + and H 2 CO + relative to C + was also increased.
Beispiel 3Example 3
Unter vergleichbaren Bedingungen wie in Beispiel 2 wurde die H2O+ - Ausbeute in die von dem evolutionären Algorithmus verwendete Fitness-Funktion integriert. Das Opti- mierungsexperiment wurde mit dem gewählten Ziel durchgeführt, das Verhältnis CH+/ H2O+ zu maximieren. Durch die Optimierung der Laserpulsform mittels des evolutionären Algorithmus konnte der H2O+ - Peak relativ zu dem C+ - Peak um ca. 50% reduziert werden. Vor der Optimierung war der H2O+ - Peak größer als der CH+ - Peak. Dieses Verhältnis konnte durch den optimierten geformten Laserpuls umgekehrt werden. Die CO+- und HCO+- Peak Intensitäten wurden erhöht, wohingegen sich CH+ Und CH2 + praktisch nicht relativ zu C+ veränderten. Auch bei diesem Experiment konnte durch eine Intensitätsänderung eines ungeformten Laserpulses keine Reduzierung des H2O+- Signals relativ zu den anderen Peaks erreicht werden.Under comparable conditions as in Example 2, the H 2 O + yield was integrated into the fitness function used by the evolutionary algorithm. The optimization experiment was carried out with the chosen goal of maximizing the ratio CH + / H 2 O + . By optimizing the laser pulse shape using the evolutionary algorithm, the H 2 O + peak could be reduced by about 50% relative to the C + peak. Before optimization, the H 2 O + peak was larger than the CH + peak. This ratio could be reversed by the optimized shaped laser pulse. The CO + and HCO + peak intensities were increased whereas CH + and CH 2 + did not change much relative to C + . In this experiment as well, it was not possible to reduce the H 2 O + signal relative to the other peaks by changing the intensity of an unshaped laser pulse.
Die in diesen Beispielen beschriebenen Ergebnisse zeigen deutlich, dass ein evolutionärer Algorithmus für eine Optimierung der Pulsform von geformten ultrakurzen Laserpulsen zum Steuern zweier konkurrierender Reaktionskanäle, in welchen Molekülbindungen entstehen und nicht einfach aufgetrennt werden, verwendet werden kann.The results described in these examples clearly demonstrate that an evolutionary algorithm for optimizing the pulse shape of shaped ultrashort laser pulses can be used to control two competing reaction channels in which molecular bonds are formed rather than simply resolved.
Folglich kann die katalytische Synthese von Produktmolekülen selektiv durch das erfindungsgemäße Verfahren gesteuert werden. BezuqszeichenlisteThus, the catalytic synthesis of product molecules can be selectively controlled by the method of the invention. LIST OF REFERENCES
1 Laser1 laser
2 Laserpulse2 laser pulses
3 ungeformte Laserpulse3 unshaped laser pulses
4 erstes Gitter4 first grid
5 erste Linse5 first lens
6 divergente Strahlen6 divergent rays
7 paralleles Strahlenbündel7 parallel beam
8 Flüssigkristalldisplay8 liquid crystal display
9 zweite Linse9 second lens
10 Strahlenbündel10 beams
1 1 zweites Gitter1 1 second grid
12 Laserpulse12 laser pulses
13 geformte Laserpulse13 shaped laser pulses
14 Pulsformer14 pulse shaper
15 Oberfläche15 surface
16 CO-Reservoir16 CO reservoir
17 H2-Reservoir17 H 2 reservoir
18 Gemisch18 mixture
19 Düse19 nozzle
20 Skimmer20 skimmers
21 Gas21 gas
22 Produktmoleküle22 product molecules
23 Flugzeitmassenspektrometer23 time-of-flight mass spectrometer
24 Detektor24 detector
25 Signale25 signals
26 Verbindung26 connection
27 Ionen27 ions
28 Rechner 28 computers

Claims

Patentansprüche claims
1. Verfahren zur Synthese von Produktmolekülen, dadurch gekennzeichnet, dass mit Hilfe eines Pulsformers geformte ultrakurze Laserpulse erzeugt werden und ein Gas, das Eduktmoleküle enthält, auf eine Oberfläche geleitet wird, auf der die1. A process for the synthesis of product molecules, characterized in that formed by means of a pulse shaper formed ultrashort laser pulses and a gas containing educt molecules is passed to a surface on which the
Eduktmoleküle zumindest teilweise adsorbiert werden, wobei die geformten ultrakurzen Laserpulse auf die Oberfläche gelenkt werden, um einen Reaktionsverlauf zur Synthese der Produktmoleküle aus auf der Oberfläche adsorbierten Edukten zu steuern.Eduktmoleküle be at least partially adsorbed, wherein the shaped ultrashort laser pulses are directed to the surface to control a reaction course for the synthesis of the product molecules of adsorbed on the surface of educts.
2. Verfahren gemäß Anspruch 1 , dadurch gekennzeichnet, dass der Pulsformer spektrale Anteile von Laserpulsen in Bezug auf Intensität und Phase formt.2. The method according to claim 1, characterized in that the pulse shaper forms spectral components of laser pulses with respect to intensity and phase.
3. Verfahren gemäß einem der Ansprüche 1 oder 2, dadurch gekennzeichnet, dass der Pulsformer spektrale Anteile von Laserpulsen in Bezug auf Polarisation formt.3. The method according to any one of claims 1 or 2, characterized in that the pulse shaper forms spectral components of laser pulses with respect to polarization.
4. Verfahren gemäß einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, dass während der Synthese eine Optimierung der geformten ultrakurzen Laserpulse erfolgt durch Messen mittels eines Detektors, welche Produkte mit welchen Aus- beuten bei der Synthese der Produktmoleküle entstehen, Generieren einer geänderten Pulsform mittels eines Rechners durch einen Optimierungsalgorithmus und Ansteuern des Pulsformers, so dass die geformten ultrakurzen Laserpulse mit der geänderten Pulsform erzeugt werden.4. The method according to any one of claims 1 to 3, characterized in that during the synthesis, an optimization of the shaped ultrashort laser pulses takes place by measuring by means of a detector, which products with which yields in the synthesis of the product molecules, generating a modified pulse shape means a computer by an optimization algorithm and driving the pulse shaper, so that the shaped ultrashort laser pulses are generated with the changed pulse shape.
5. Verfahren gemäß einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, dass die Laserpulse durch einen Pulsformer geformt werden, der auf einer rechnergesteuerten Technik beruht, die ein Ansteuern von mindestens einer Einrichtung ausgewählt aus der Gruppe Flüssigkristalldisplay, akusto-optischer Modulator, akusto-optischer Filter, verformbarer Spiegel und Mikrospiegelanordnung um- fasst.5. The method according to any one of claims 1 to 4, characterized in that the laser pulses are formed by a pulse shaper, which is based on a computer-controlled technique, the driving of at least one device selected from the group of liquid crystal display, acousto-optic modulator, acousto optical filter, deformable mirror and micromirror arrangement.
6. Verfahren gemäß einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, dass das Gas auf eine Oberfläche geleitet wird, die eine Einkristalloberfläche eines Übergangsmetalles ist.6. The method according to any one of claims 1 to 5, characterized in that the gas is passed onto a surface which is a single crystal surface of a transition metal.
7. Verfahren gemäß einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, dass ein Gas auf die Oberfläche geleitet wird, das eine oder mehrere Sorten von Eduktmolekülen enthält. 7. The method according to any one of claims 1 to 6, characterized in that a gas is passed to the surface containing one or more types of educt molecules.
8. Verfahren gemäß einem der Ansprüche 1 bis 7, dadurch gekennzeichnet, dass ein Gas auf die Oberfläche geleitet wird, das ein Gemisch aus mindestens zwei Sorten von Eduktmolekülen enthält, wobei ein Verhältnis von Massenströmen der mindestens zwei Sorten von Eduktmolekülen durch eine Regeleinrichtung gere- gelt wird.8. The method according to any one of claims 1 to 7, characterized in that a gas is passed to the surface containing a mixture of at least two types of reactant molecules, wherein a ratio of mass flows of the at least two types of reactant molecules by a control device regulated is valid.
9. Verfahren gemäß einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, dass ein Gas auf die Oberfläche geleitet wird, das mindestens eine Sorte von Eduktmolekülen ausgewählt aus der Gruppe Aceton, Acetylen, Ameisensäure, Ammo- niak, Arsin, Blausäure, Bortrichlorid, Bortrifluorid, Bromethen, Brommethan,9. The method according to any one of claims 1 to 8, characterized in that a gas is passed to the surface, the at least one kind of Eduktmolekülen selected from the group acetone, acetylene, formic acid, ammonia, arsine, hydrocyanic acid, boron trichloride, boron trifluoride , Bromothene, bromomethane,
Bromwasserstoff, 1.3-Butadien, Butan, 1-Buten, 1-Butin, Chlor, Chlordifluor- methan, Chlorethen, Chlormethan, Chlorwasserstoff, cis-2-Buten, Deuterium, Dichlorsilan, Diethylether, Difluormethan, Dimethylamin, Dimethylether, 2,2- Dimethylpropan, Disilan, Distickstoffmonoxid, Stickoxydul, Ethan, Ethen, Ethy- lenoxid, Fluormethan, Formaldehyd, Hexafluorethan, Isobutan, Isobuten, Kohlendioxid, Kohlenmonoxid, Methan, Methanol, Methylamin, Octafluorcyclobutan, Octafluorpropan, Phosphin, Propan, Propen, 1 -Propin, Propylenoxid, Sauerstoff, Schwefeldioxid, Schwefelhexafluorid, Schwefelwasserstoff, Silan, Silicium- tetrafluorid, Stickstoff, Stickstoffdioxid/Distickstofftetroxid, Stickstoffmonoxid, Stickstofftrifluorid, Tetrafluormethan, trans-2-Buten, Trifluormethan, Trimethyla- min und Wasserstoff enthält.Hydrogen bromide, 1,3-butadiene, butane, 1-butene, 1-butyne, chlorine, chlorodifluoromethane, chloroethene, chloromethane, hydrogen chloride, cis-2-butene, deuterium, dichlorosilane, diethyl ether, difluoromethane, dimethylamine, dimethyl ether, 2,2- Dimethylpropane, disilane, dinitrogen monoxide, nitric oxide, ethane, ethene, ethylene oxide, fluoromethane, formaldehyde, hexafluoroethane, isobutane, isobutene, carbon dioxide, carbon monoxide, methane, methanol, methylamine, octafluorocyclobutane, octafluoropropane, phosphine, propane, propene, propotin, Propylene oxide, oxygen, sulfur dioxide, sulfur hexafluoride, hydrogen sulfide, silane, silicon tetrafluoride, nitrogen, nitrogen dioxide / dinitrogen tetroxide, nitric oxide, nitrogen trifluoride, tetrafluoromethane, trans-2-butene, trifluoromethane, trimethylamine and hydrogen.
10. Verfahren gemäß einem der Ansprüche 1 bis 9, dadurch gekennzeichnet, dass das Gas in einer Vakuumkammer auf die Oberfläche geleitet wird. 10. The method according to any one of claims 1 to 9, characterized in that the gas is passed in a vacuum chamber on the surface.
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