CN112259440B - Ionization mass spectrometry device and method in vacuum ultraviolet light - Google Patents
Ionization mass spectrometry device and method in vacuum ultraviolet light Download PDFInfo
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/04—Arrangements for introducing or extracting samples to be analysed, e.g. vacuum locks; Arrangements for external adjustment of electron- or ion-optical components
- H01J49/0495—Vacuum locks; Valves
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/02—Details
- H01J49/10—Ion sources; Ion guns
- H01J49/14—Ion sources; Ion guns using particle bombardment, e.g. ionisation chambers
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J49/00—Particle spectrometers or separator tubes
- H01J49/26—Mass spectrometers or separator tubes
- H01J49/34—Dynamic spectrometers
- H01J49/42—Stability-of-path spectrometers, e.g. monopole, quadrupole, multipole, farvitrons
- H01J49/4205—Device types
- H01J49/421—Mass filters, i.e. deviating unwanted ions without trapping
Abstract
The application provides a vacuum ultraviolet light internal ionization mass spectrometry device and a mass spectrometry method, comprising the following steps: an ultraviolet light source, a mass analyzer, a beam conditioning component, an analysis sample, and a controller; the ultraviolet light source is capable of single photon ionization of the analysis sample; the mass analyzer is capable of internally performing a complete mass spectrometry operation sequence from ionization of an analysis sample to ion mass separation; the mass analyzer is provided with a light source introduction port; the light beam adjusting component is arranged at the upstream of the light source introducing port; the controller can synchronously control the working time sequence stage of the quality analyzer and the modulation quantity of the light beam regulating component; the application adopts a simple valve or light modulation structure, can use a high-sensitivity internal ionization analysis mode in vacuum ultraviolet ionization mass spectrometry, and simultaneously avoids the interference of a background noise signal caused by the traditional continuous ultraviolet light source ionization method. The limit of analytical detection can be increased by about 2-3 orders of magnitude.
Description
Technical Field
The application relates to the technical field of mass spectrometry, in particular to a vacuum ultraviolet internal ionization mass spectrometry device and a mass spectrometry method. In particular to a miniature mass spectrometry device and a miniature mass spectrometry method for realizing ionization of a sample to be tested and reducing interference in a mass analysis stage by a miniature continuous ultraviolet ionization light source.
Background
Mass spectrometry technology is widely used in public safety, biological medicine, advanced material analysis, development and other fields. Wherein, the small and micro mass spectrometry system becomes an important analysis means in the field analysis application in the fields of national defense security, other industrial civilian use and the like. The main principle of the current portable field mass spectrum full analysis mainly depends on the gas chromatography-mass spectrum combined technology is that a gas phase sample or other phase samples which can be introduced into analysis are gasified and introduced into a chromatographic column, and are separated into basically pure compounds in the separation time according to the difference of the retention or adsorption conditions of different sample molecules on the chromatographic column; and ionizing the sample molecular fragments by means of electron bombardment ionization (EI) and the like to form a mass spectrogram, and inquiring and comparing the mass spectrogram with a mass spectrogram of a standard substance to obtain quantitative information of a series of compounds. The method has good measurement accuracy, but the equipment has a plurality of challenges in the engineering of the miniaturized field below 10kg due to a series of complex devices such as a sample inlet, a sampling pump, a quantitative ring, a chromatographic column, a mass spectrum interface, an electron bombardment ionization source, a lead-in lens, a mass analyzer and the like which are required by chromatography and mass spectrum. In particular to the application fields of space load and the like with strict requirements on the mass power consumption of the system, the further miniaturization of equipment is very difficult, and a large number of tiny parts in the system cause great limitation on the stress load of the mass spectrometry system. Therefore, a new mass spectrum full analysis device is needed to meet the requirements of the advanced fields such as aerospace and the like on the miniaturization of mass spectrum systems.
In complex sample environments, the problem of fragmentation of sample molecules is mainly existed in the traditional mass spectrum total analysis method which does not depend on the pre-separation technology such as chromatography. Taking the EI source as an example, sample molecules in the ion source are capable of generating a large number of ions under the action of 70 electron volt (eV) electron bombardment ionization. However, the energy transfer of the process is violent, the chemical bond energy level of the compound exceeds that of a plurality of eV, and ions with larger energy can spontaneously crack to generate more fragments when colliding with neutral molecules. For example, common plasticizers, phthalate esters, form 149u fragments, hydrocarbon compounds form 43, 57u and other common hydrocarbon fragments, and a large number of fragments form a chemical signal that cuts down the sample molecules and interfere with each other.
Compared with EI ionization method, vacuum ultraviolet ionization (VUV-PI) has extremely low ion fragment yield, and water vapor, nitrogen and oxygen in the earth atmosphere and main background interference such as carbon dioxide in the earth atmosphere, methane in the earth atmosphere and the like are not ionized under the action of 10.6eV photons output by common continuous krypton discharge vacuum ultraviolet lamps. Therefore, the mass spectrogram obtained by adopting the VUV-PI ionization method has clean chemical background, and the molecular weight information of the ionizable sample can be directly obtained. According to the obtained molecular weight information as a basis, further chemical information of each substance can be obtained through a cascade mass analyzer such as an ion trap and a high-resolution mass analyzer such as a time-of-flight mass spectrum, so that high-efficiency full-spectrum rapid analysis is achieved.
However, compared with other ionization technologies, the laser source which can be miniaturized is not provided in the vacuum ultraviolet (wavelength 10-195 nm) region, and currently, the means such as excimer laser, inert gas ion laser, free electron laser and the like which are mainly applied all need huge test devices, and the laser method has low photon energy and is unfavorable for obtaining ionization mass spectrum information of main substances. At present, the field is mainly based on a direct current or radio frequency hollow discharge lamp to obtain vacuum ultraviolet photons with the energy of more than 8 eV. The continuous discharge method is proved to be a stable vacuum ultraviolet light generation method by using mature products of various light source enterprises such as greetings and the like, but the starting and arc extinguishing processes of the discharge process can be subjected to an unstable process of a few milliseconds to sub-seconds.
Patent document CN1811408B proposes an ion trap mass spectrometry method for analyzing and detecting a sample by internal photoionization, but a miniature mass spectrometry device and a method thereof which can truly perform high-sensitivity internal ionization mode analysis are not yet available at present because of the great difficulty in pulse generation stability of vacuum ultraviolet light.
The main reasons for this problem are: the instability of the light source in the ionization stage of the mass analyzer sample and the strong background noise caused by the continuous ionization of the substances in the mass analyzer by the continuously input vacuum ultraviolet light in the mass analysis stage. In fact, especially because the vacuum ultraviolet light input in the mass analysis stage cannot be stopped smoothly, the improvement of the relative sensitivity and the detection limit of mass spectrum detection which are supposed to be brought by the internal ionization method are not realized basically. Therefore, it is necessary to find a micro mass spectrometry device and method that overcomes the instability of time-series control of vacuum ultraviolet light, improves the signal repeatability in the ionization stage of the internal ionization mass spectrometry, and eliminates the photoionization background noise in the mass analysis stage.
Disclosure of Invention
Aiming at the defects in the prior art, the application aims to provide a vacuum ultraviolet internal ionization mass spectrometry device and a mass spectrometry method.
The vacuum ultraviolet light internal ionization mass spectrum analysis device provided by the application comprises: an ultraviolet light source, a mass analyzer, a beam conditioning component, an analysis sample, and a controller;
the ultraviolet light source is capable of single photon ionization of the analysis sample;
the mass analyzer is capable of internally performing a complete mass spectrometry operation sequence from ionization of an analysis sample to ion mass separation;
the mass analyzer is provided with a light source introduction port;
the light beam adjusting component is arranged at the upstream of the light source introducing port;
the controller can synchronously control the working time sequence stage of the quality analyzer and the modulation quantity of the light beam regulating component;
the ultraviolet light source adopts a continuous vacuum ultraviolet light source;
the working time sequence stage synchronously controlled by the controller comprises any one or more of the following steps:
-sample ionization;
-ion kinetic energy modulation;
ion separation of different mass to charge ratios.
Preferably, the mass analyser employs an ion trap mass analyser, the enrichment of ions of interest within the ion trap being achieved by controlling the electrode voltage of the ion trap.
Preferably, the ion trap is also included;
the illumination direction of the ultraviolet light source and the axis of the direction of the analysis sample entering the ion trap are mutually overlapped.
Preferably, the ion trap is a cylindrical or square high capacity ion trap.
Preferably, the ion kinetic energy regulating voltage of the mass analyser is a periodic square wave or pulse.
Preferably, the ion kinetic energy regulating voltage of the mass analyser is a periodic square wave or pulse.
Preferably, the method further comprises: a sample injection valve;
and the opening time sequence of the sample injection valve is synchronous with the high conduction time sequence of the light beam adjusting component.
Preferably, the beam adjusting component makes vacuum ultraviolet light output by the continuous vacuum ultraviolet light source bombard the surface with electron work function lower than vacuum ultraviolet photon energy for at least a part of time, generate escaping photoelectrons and ionize at least a part of sample molecules and background gas molecules in the vacuum ultraviolet light ionization mass spectrometry device.
Preferably, the method further comprises: a collecting electrode and an ion multiplying unit;
the collecting electrode can detect the vacuum degree;
the collecting electrode can collect a current signal formed by ions formed by ionization of at least part of sample molecules and background gas molecules in the vacuum ultraviolet light ionization mass spectrum analysis device, the current signal is used for being input into the controller, whether the internal air pressure of the vacuum ultraviolet light ionization mass spectrum analysis device meets the high-voltage safe working threshold range of the ion multiplication component is calculated, and the working high voltage of the ion multiplication component is controlled to be switched on and off according to a threshold judgment result.
Preferably, the ionization mass spectrometry device in vacuum ultraviolet light is adopted, comprising:
step S1: starting the continuous vacuum ultraviolet light source, and keeping the intensity of the output vacuum ultraviolet light within a range of +/-1% of the preset average output value;
step S2: the working condition of the mass analyzer is controlled by a controller, so that the mass analyzer enters a sample ionization working stage, and a sample introduced into the mass analyzer is ionized into sample ions under the action of output vacuum ultraviolet light, and meanwhile, the sample ions still reside in the mass analyzer;
step S3: the controller is adopted to control the light beam regulating component, so that the intensity of the vacuum ultraviolet light entering the mass analyzer is reduced to 1% or less of the average output value set by the continuous vacuum ultraviolet light source;
step S4: the working condition of the mass analyzer is controlled by a controller, so that the mass analyzer enters an ion kinetic energy adjusting stage, and the kinetic energy of sample ions residing in the mass analyzer is adjusted, so that the ion kinetic energy and potential energy distribution state for separating ions with different mass to charge ratios are met;
step S5: and the working conditions of the mass analyzer are controlled by a controller, so that the mass analyzer enters an ion separation stage with different mass-to-charge ratios, and sample ion electric signals with different mass-to-charge ratios are separated according to the mass number sequence, so that a mass spectrogram is obtained.
Compared with the prior art, the application has the following beneficial effects:
1. the application adopts a simple valve or light modulation structure, can use a high-sensitivity internal ionization analysis mode in vacuum ultraviolet ionization mass spectrometry, and simultaneously avoids the interference of a background noise signal caused by the traditional continuous ultraviolet light source ionization method. The analysis detection limit can be improved by about 2-3 orders of magnitude;
2. the application can further reduce the influence of the neutral noise of the sample on the mass spectrometry of the extremely low-content vacuum residual gas by arranging the same on-off ultraviolet light path and the valve type modulation device for sample incidence. The method can also reduce the load of the vacuum chamber where the mass spectrum analyzer is positioned, reduce the cost of the vacuum pump set and reduce the volume and weight of the whole machine when the vacuum pump set is used for analyzing the load;
3. the application has reasonable structure and convenient use, and can overcome the defects of the prior art.
Drawings
Other features, objects and advantages of the present application will become more apparent upon reading of the detailed description of non-limiting embodiments, given with reference to the accompanying drawings in which:
fig. 1 is a timing diagram of the structure and operation of a conventional ionization mass spectrometry apparatus in a prior vacuum uv source.
Fig. 2 is a schematic diagram of a prior vacuum ultraviolet light source external ionization mass spectrometry apparatus.
Fig. 3 is a structural and operational timing diagram of an exemplary embodiment of the present application.
Fig. 4a is a schematic diagram of a cylindrical ion trap that may be used in an embodiment of the present application.
Fig. 4b is a schematic diagram of a square ion trap that may be used in an embodiment of the present application.
Fig. 4c is a schematic diagram of a time-of-flight mass analyzer that may be used with embodiments of the present application.
FIG. 5 is a schematic diagram of a sample dioctyl phthalate 391u spectral analysis in accordance with an exemplary embodiment of the present application.
FIG. 6a is a structural and operational timing diagram of an improved embodiment of the present application employing valves to further enhance the synchronization performance of sample analysis.
Fig. 6b is a structural and operational timing diagram of an improved embodiment of the present application employing valves as both the feed and uv modulated internal ionization processes.
FIG. 7 is a schematic diagram of the structure and light intensity-noise-deflection voltage optimization relationship of an improved embodiment of the present application using a deflection voltage device as an ultraviolet light modulator.
FIG. 8 is a block diagram of an improved embodiment of the ionization analysis sample range of the apparatus of the present application utilizing the gated off or masked ultraviolet light portion to generate escaping photoelectrons, through electron capture or post-acceleration ionization of the electrons.
FIG. 9 is a structural and operational timing diagram of a stability improvement embodiment of the present application for controlling the switching of the operating high voltage of the ion multiplication element by collecting the current signal from the ionization of the sample and background gas molecules in the portion of the UV light portion that is blocked or masked by the UV light portion, and calculating whether the internal gas pressure of the UV internal photoionization mass spectrometry device meets the high voltage safe operating threshold range of the ion multiplication element.
Detailed Description
The present application will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the present application, but are not intended to limit the application in any way. It should be noted that variations and modifications could be made by those skilled in the art without departing from the inventive concept. These are all within the scope of the present application.
In the current common mass spectrometer, as shown in fig. 1, the sample gas molecules are freely dissipated in the vacuum chamber after entering the mass spectrometer, and ionized to form more complete charged particles when passing through the beam generated by the ultraviolet light source 101, and enter the mass analyzer through the charged particle channel in the center of the ion trap. In this common design, since it is currently difficult to achieve microminiature laser illuminant, especially vacuum ultraviolet light sources with photon energy above 8eV (electron volts), there is no reasonable solution to the dissipation power below 10W, which can only be achieved with continuous discharge type Ar/Kr lamps.
Taking the linear ion trap mass analyzer 102 as shown in the figure as an example, one end of the axis 103 direction of the linear ion trap mass analyzer is provided with a light source introduction port 104, through an external control circuit 105 of the mass analyzer, ion gate voltages can be added to two end covers 106 and 107 of the linear ion trap, and constraint radio frequency RF and excitation alternating current voltages AC can be respectively added to two pairs of constraint radio frequency electrodes 108 and 109 of the linear ion trap. As can be seen from the timing diagram of the various voltages applied in fig. 1, the mass analyzer operating phase includes at least 3 timing phases: a) Sample ionization 1001; b) Ion kinetic energy cooling adjustment 1002; c) Ion separation 1003 of different mass to charge ratios.
According to the principles of the internal ionization mass spectrometry apparatus, the incident vacuum ultraviolet light only needs to ionize the mass analyzer 102 at ionization time sequence stage 1001. Because of the starting 1010 and the extinguishing stage 1020 of the operating sequence of this type of gas discharge lamp, the establishment or stopping of the discharge process is accompanied by a highly random process of random ionization propagation or quenching. The vacuum ultraviolet photons that continue into the mass analyzer during the time sequence stage 1002 or 1003 in the figure, without introducing ions, will create additional background ionization or penning processes for the internal background gas. Particularly, the introduction of additional vacuum ultraviolet light in the ion separation timing stage 1003 with different mass-to-charge ratios can continuously generate uncontrolled stray ions or neutral excited state species signals in the mass analyzer, so that the mass spectrometry efficiency of the ionization device in the type is seriously affected, and the internal impurity ions can occupy a constraint potential well in the mass analyzer, so that space charge effect is generated to influence the ionization efficiency of the sample ionization timing stage in the next period. Therefore, the ionization efficiency of the sample gas molecules and the final detection sensitivity of the mass analyzer are low in this design, so a design scheme for improving the ionization and analysis efficiency needs to be considered.
The conventional solution is to use the external ionization scheme shown in fig. 2, and use an external additional ion source 210 to make the light path emitted by the continuous ultraviolet light source 201 perpendicular to the optical axis of the mass analyzer 202, so as to reduce the influence of the continuously emitted vacuum ultraviolet light on the mass analyzer in the ionization time sequence stage of the non-sample as much as possible. However, such mass spectrometry apparatus require the introduction of ions from outside the mass analyzer, introducing additional external ion source volume and dynamic circuit consumption of the ion lens/end cap ion gate. In addition, for a radio frequency trap type mass analyzer, effective external trapping of ions requires the assistance of an internal collision gas, typically at a pressure of 10 -1 -10 -4 Pa range. For higher vacuum outer satellites such as lunar surfaces or 10 -5 Space environment simulation device with Pa and below vacuum degree, and typical molecular mean free path is far greater than 10 -2 -10 -1 Mass analyzers on the order of meters feature size, which results in poor sensitivity or no use at all for such analyzers. This is very disadvantageous for realizing a lightweight and small space and ground analysis device.
To solve this problem, as shown in fig. 3, a basic embodiment of the present application provides a vacuum ultraviolet in-uv ionization mass spectrometry apparatus, comprising: at least one continuous vacuum ultraviolet light source for single photon ionization of analytes, such as a krypton-filled hollow dc discharge lamp 301 in this embodiment, injects ultraviolet light into the mass analyzer 302 axis 303 for complete mass spectrum operation timing for sample ionization to ion mass separation; at least one beam adjusting component 310 for adjusting the intensity of the vacuum ultraviolet light incident on the mass analyzer, in this case an optical chopper, can modulate the intensity variation of the ultraviolet light by changing the position or direction state of the beam adjusting component, and further control the ionization condition of the sample molecules; at least one controller 310 for controlling the operation of the mass analyzer 302 and the beam conditioning unit 301 synchronously. By means of the mass analyser external control circuit 305, ion gate electrostatic voltages can be applied to the two end caps 306, 307 of the linear ion trap, an adjustment enable signal can be applied to the adjustment means, and a confining RF and excitation AC voltage AC can be applied to the two pairs of confining RF electrodes 308 and 309, respectively. The mass analyzer operating phase includes at least 3 sequential phases: a) Sample ionization 3001; b) Ion kinetic energy cooling adjustment 3002; c) Ions of different mass to charge ratios are separated 3003.
In one embodiment of this embodiment, the device is a chopper plate, i.e., a rotatable wafer with light passing notches, made of a metal or non-metal light absorbing material that is non-conductive to the vacuum ultraviolet light source. When the mass spectrometer starts to work, sample gas molecules enter the vacuum cavity from a notch on the sample inlet 304 or other mass analyzers, the molecules are freely diffused and converged with the vacuum ultraviolet light beam emitted by the light source, and the sample gas molecules in the central ion channel are ionized by ultraviolet irradiation and enter the analysis chamber after free flight. The method has the advantage that the problems of photo-generated noise in the time sequence stage of ion separation work of different mass to charge ratios or ion kinetic energy cooling adjustment of a mass analyzer are not avoided. The axis 303 of the analyzer can be coincident with the ultraviolet beam at a small angle, even completely coaxial, so as to greatly increase the number of sample ions entering the analysis chamber and directly increase the signal intensity.
In the example, the position of the optical chopper plate 310 can be adjusted by a controller, and the controller 310 can pulse the emitted ultraviolet light by changing the rotation frequency of the chopper, so that the ionized sample gas ion beam also has a certain characteristic and can be matched with the analysis work of the mass analyzer.
It should be noted that the mass analyzers of different weights are applicable under the method of the apparatus, as shown in fig. 4, and the mass analyzers in this embodiment may be cylindrical ion traps 410 or square ion traps 420, and in particular, after the square ion trap structure is adopted, the structural characteristics of the ion traps are easily implemented by micro-mechanical micromachining (MEMS) technology, so that consistency and repeatability of the mass spectrum microstructure can be ensured under the micron scale. In addition, the mass analyzer may also be a micro time-of-flight mass analyzer 430, also fabricated in a MEMS process, that includes an ionization acceleration region electrode 4301, a silicon gate mesh 4302, a laminated mirror 4303, and a planar time-focusing microchannel detector 4304. Because the modulation device is adopted to control the continuous vacuum ultraviolet light source, the ion beam obtained by ionization can be overlapped with the ultraviolet light beam, the detection efficiency of the analyzer is further improved, the planar micro-channel detector 4304 and the acceleration region electrode 4301 can be processed on the same substrate by using the MEMS technology, the influence of photo-generated noise is avoided, and the integral processing precision of the quality analyzer is improved.
Fig. 5 shows the analysis effect of conventional vacuum ultraviolet ionization by using a square linear ion trap with a length dimension of 22 mm, which is formed by constructing 4 rectangular plane electrodes by coating films on 4 high vacuum insulating resins, wherein the field radius in the emergent x direction is measured to be 1.62mm, and the field radius in the vertical y direction is measured to be 1.39mm. Parallel slots with the width of 0.2mm are formed in the emergent direction, and the structure is identical to that shown in fig. 1/3. When the external ionization mode is used, the voltages of the front 3 focusing lenses are respectively-88V, -3.8V and-1V, the ion optical structure is shown in figure 2, the voltage of the front end cover of the ion trap is 1V in the ionization time sequence stage of the sample, and the voltage of the rest ion kinetic energy cooling adjustment and the time sequence stage of ion separation with different mass to charge ratios is 15V. In the internal ionization mode, the end caps were all at 15V.
Fig. 5a shows an analytical mass spectrum using conventional continuous uv injection, with a response to the analyte dioctyl phthalate 391u of up to 2x104, but with a large base photoionization noise due to continuous uv injection, the signal to noise ratio under background noise is only 8: about 1. The result of the modification of the vertical external ionization source introduction structure shown in fig. 2 is shown in fig. 5b, in which the photoionization noise is reduced to about 50-80 due to the vertical structure, but the signal strength is also reduced to 2.3x103 due to the external introduction interface loss, and the signal to noise ratio is restored to about 29:1.
the analysis mass spectrum obtained under the device of fig. 3 of the additional ultraviolet light modulating device provided by the application is shown in fig. 5c, because the beam modulating device 310 formed by the chopper directly intercepts the ultraviolet light beam introduction in the non-ionization time sequence stage on the mass spectrum light path, the signal background noise is directly reduced to the order of magnitude of units. Meanwhile, the 391u response height of the analyte dioctyl phthalate can still be kept at 1.8x104, the overall signal to noise ratio is improved to about 5000:1, and the effect is very obvious.
To further enhance the synchronization performance of sample analysis, as shown in fig. 6a, the sample to be analyzed of the mass spectrum may be introduced and synchronized with the light modulation device, for example, by the controller 605, a sample introduction valve 612 is controlled to synchronize the opening timing of the modulator controller 310 and the chopper 311 with the opening timing of the valve 612. Thus, the sample substance can be more effectively utilized in the sample introduction process, and the influence of other secondary ionization processes, such as penning ionization of metastable substances on the residual sample, charge transfer ionization and the like on the mass analysis process is avoided.
In a further improved embodiment, in fig. 6b, the beam adjusting component may be the sample injection valve plate 612 itself, in which the body is a gate that uses the armature 613 to move the sample injection valve plate 612 under the control of the driving coil 611, the uv light passing rate can be changed by changing the gate position, and the beam adjusting component synchronously works with the mass analyzer under the coordination of the synchronous controller, and the periodic opening and closing can modulate the uv light to achieve the effect similar to that of the chopper, thereby further reducing the complexity of the system, and simultaneously spontaneously realizing the timing synchronization of sample opening introduction and vacuum uv ionization photon introduction.
The disadvantage of the above embodiment is that the physical modulator needs to be introduced to modulate the ultraviolet light, which itself occupies a certain volume in the overall structure of the device, which is unfavorable for miniaturization, and the possibility of abrasion and failure occurrence cannot be eliminated when the physical device works, and once the failure occurs, the whole set of device cannot work normally. Thus in a modified embodiment of the application, the original chopper is replaced with a deflection voltage 715 applied to deflection electrodes 713, 714 on both sides of the uv light source, as shown in fig. 7a, with the remaining components unchanged; the ultraviolet light is modulated by controlling the intensity of the electric field and changing the frequency, and the electric field acts on the ultraviolet light without the operation of an entity device, so that the difficulty in design and the possibility of faults are reduced, the stability and durability of the whole set of device are improved, and meanwhile, the modulation is more accurate and reliable. Fig. 7b shows the modulation effect of the electric field modulation light source device on the ionization efficiency of the output ultraviolet light, and it can be seen that when the deflection voltage 715 is above 510V, the output ultraviolet light intensity 720 has fallen below 1% of the normal value. At this time, the secondary noise signal 721 generated by the photoionization is reduced to an effect similar to that of fig. 5c, thereby achieving the technical effect of improving the signal sensitivity of the spectrometer.
It is also noted that continuous vacuum ultraviolet light by deflection or valve gating may also be utilized, such as to bombard surfaces where the electron work function is below its vacuum ultraviolet photon energy for at least a portion of the time. This process may generate escaping photoelectrons that may ionize at least a portion of the sample molecules and background gas molecules 800 within the ultraviolet photoionization mass spectrometry device by electron capture or post-acceleration ionization of electrons. As shown in FIG. 8, after the electric potential of the upper and lower 3 lenses 801, 802 and 803 is changed to 8V,7V and-60V, the emergent ultraviolet light excites photo-generated electrons on the third small hole lens 803 and the light modulation chopper 311 with-60V, and then the photo-generated electrons are accelerated to the interval between the first lens 801 and the second lens 802 to obtain about 70eV energy, and various substances can be ionized to form ions 804 due to no obvious substance energy threshold value of electron capture or post-acceleration ionization, so that the substance range of the sample analysis device is expanded.
Besides the mass spectrum signal obtained by the method, the device or the method can be designed into an endogenous vacuum gauge through reasonable design as shown in figure 9 because vacuum ultraviolet ionization and photo-generated electron ionization thereof have no vacuum degree requirement limit of cold cathode, hot filament or field emission ionization. In this design, the device further comprises a collector 901 for detecting vacuum degree and an ion current multiplier 902 for collecting a current signal 903 formed by ionization of the sample molecules and the background gas molecules, which is used for inputting the current signal 903 to the controller to calculate the internal air pressure of the ultraviolet internal photoionization mass spectrum analyzer. After the air pressure value is obtained, by calculating whether the air pressure value meets the high voltage safe operation threshold 904 of the ion multiplication component, the operation high voltage 905 of the ion multiplication component can be controlled to be switched according to the threshold judgment result, so that the high-value ion/electron multiplier 906 in the equipment is protected from damage.
In general, in various embodiments of the present application, a mass spectrometry method using the vacuum ultraviolet internal photoionization mass spectrometry device is formed, for which typical working sequence steps and conditions are as follows:
a) Starting the continuous vacuum ultraviolet light source (101 or 301), keeping the intensity of the output vacuum ultraviolet light stable, and setting the recommended value to be within the range of +/-1% of the preset average output value;
b) The controller (305 or 605) controls the operating conditions of the mass analyzer (302 or 410, 420, 430) to enter a sample ionization operating phase and ionize a sample introduced into the mass analyzer into sample ions under the action of the output vacuum ultraviolet light while still residing in the mass analyzer;
c) The controller controls the beam adjusting part (311 or 612) to reduce the intensity of the vacuum ultraviolet light entering the mass analyzer to 1% or less of the average output value set by the continuous vacuum ultraviolet light source;
d) The controller controls the operating conditions of the mass analyser (302 or 410, 420, 430) to enter an ion kinetic energy adjustment stage to adjust the kinetic energy of sample ions residing in the mass analyser to meet ion kinetic and potential energy distribution conditions for separating ions of different mass to charge ratios therebehind;
e) The controller controls the working conditions of the mass analyzer (302 or 410, 420, 430) to enable the mass analyzer to enter ion separation stages with different mass-to-charge ratios, so that sample ionic electric signals are separated according to the mass number sequence, and mass spectrum is obtained.
From the data analysis of fig. 5, fig. 7 and the like, the method really solves the background noise problem of the traditional low-power-consumption continuous ultraviolet internal ionization mass spectrum system, and can obviously improve the mass spectrum analysis sensitivity and analysis effect.
Those skilled in the art will appreciate that the application provides a system and its individual devices, modules, units, etc. that can be implemented entirely by logic programming of method steps, in addition to being implemented as pure computer readable program code, in the form of logic gates, switches, application specific integrated circuits, programmable logic controllers, embedded microcontrollers, etc. Therefore, the system and various devices, modules and units thereof provided by the application can be regarded as a hardware component, and the devices, modules and units for realizing various functions included in the system can be regarded as structures in the hardware component; means, modules, and units for implementing the various functions may also be considered as either software modules for implementing the methods or structures within hardware components.
In the description of the present application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and thus should not be construed as limiting the present application.
The foregoing describes specific embodiments of the present application. It is to be understood that the application is not limited to the particular embodiments described above, and that various changes or modifications may be made by those skilled in the art within the scope of the appended claims without affecting the spirit of the application. The embodiments of the application and the features of the embodiments may be combined with each other arbitrarily without conflict.
Claims (9)
1. A vacuum ultraviolet light ionization mass spectrometry device, comprising: an ultraviolet light source, a mass analyzer, a beam conditioning component, an analysis sample, and a controller;
the ultraviolet light source is capable of single photon ionization of the analysis sample;
the mass analyzer is capable of internally performing a complete mass spectrometry operation sequence from ionization of an analysis sample to ion mass separation;
the mass analyzer is provided with a light source introduction port;
the light beam adjusting component is arranged at the upstream of the light source introducing port;
the controller can synchronously control the working time sequence stage of the quality analyzer and the modulation quantity of the light beam regulating component;
the ultraviolet light source adopts a continuous vacuum ultraviolet light source;
the working time sequence stage synchronously controlled by the controller comprises any one or more of the following steps:
-sample ionization;
-ion kinetic energy modulation;
-ion separation of different mass to charge ratios;
the light beam adjusting component is an optical chopper, and can realize the modulation of ultraviolet light intensity change by changing the position or direction state of the light beam adjusting component;
the optical chopper adopts a rotatable wafer with a light-transmitting notch.
2. The apparatus according to claim 1, wherein the mass analyzer is an ion trap mass analyzer, and wherein the enrichment of ions required in the ion trap is achieved by controlling an electrode voltage of the ion trap.
3. The apparatus of claim 1, further comprising an ion trap;
the illumination direction of the ultraviolet light source and the axis of the direction of the analysis sample entering the ion trap are mutually overlapped.
4. The apparatus of claim 3, wherein the ion trap is a cylindrical or square high capacity ion trap.
5. The apparatus of claim 1, wherein the ion kinetic energy adjustment voltage of the mass analyzer is a periodic square wave or pulse.
6. The vacuum ultraviolet light internal ionization mass spectrometry apparatus according to claim 1, further comprising: a sample injection valve;
and the opening time sequence of the sample injection valve is synchronous with the high conduction time sequence of the light beam adjusting component.
7. The apparatus according to claim 1, wherein the beam adjusting means causes the vacuum ultraviolet light outputted from the continuous vacuum ultraviolet light source to bombard the surface having an electron work function lower than the energy of the vacuum ultraviolet photon for at least a part of the time, generate escaping photoelectrons, and ionize at least a part of the sample molecules and the background gas molecules in the vacuum ultraviolet light ionization mass spectrometry apparatus.
8. The vacuum ultraviolet light internal ionization mass spectrometry apparatus according to claim 1, further comprising: a collecting electrode and an ion multiplying unit;
the collecting electrode can detect the vacuum degree;
the collecting electrode can collect a current signal formed by ions formed by ionization of at least part of sample molecules and background gas molecules in the vacuum ultraviolet light ionization mass spectrum analysis device, the current signal is used for being input into the controller, whether the internal air pressure of the vacuum ultraviolet light ionization mass spectrum analysis device meets the high-voltage safe working threshold range of the ion multiplication component is calculated, and the working high voltage of the ion multiplication component is controlled to be switched on and off according to a threshold judgment result.
9. A method of mass spectrometry employing the vacuum ultraviolet in-situ ionization mass spectrometry apparatus of any one of claims 1 to 8, comprising:
step S1: starting the continuous vacuum ultraviolet light source, and keeping the intensity of the output vacuum ultraviolet light within a range of +/-1% of the preset average output value;
step S2: the working condition of the mass analyzer is controlled by a controller, so that the mass analyzer enters a sample ionization working stage, and a sample introduced into the mass analyzer is ionized into sample ions under the action of output vacuum ultraviolet light, and meanwhile, the sample ions still reside in the mass analyzer;
step S3: the controller is adopted to control the light beam regulating component, so that the intensity of the vacuum ultraviolet light entering the mass analyzer is reduced to 1% or less of the average output value set by the continuous vacuum ultraviolet light source;
step S4: the working condition of the mass analyzer is controlled by a controller, so that the mass analyzer enters an ion kinetic energy adjusting stage, and the kinetic energy of sample ions residing in the mass analyzer is adjusted, so that the ion kinetic energy and potential energy distribution state for separating ions with different mass to charge ratios are met;
step S5: and the working conditions of the mass analyzer are controlled by a controller, so that the mass analyzer enters an ion separation stage with different mass-to-charge ratios, and sample ion electric signals with different mass-to-charge ratios are separated according to the mass number sequence, so that a mass spectrogram is obtained.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103854952A (en) * | 2012-11-30 | 2014-06-11 | 中国科学院大连化学物理研究所 | Mass spectrum vacuum ultraviolet ionization source based on optical-window-free gas discharge lamp |
| CN108091545A (en) * | 2016-11-21 | 2018-05-29 | 中国科学院大连化学物理研究所 | A kind of ultraviolet light ionization source for mass spectral analysis |
| CN109841491A (en) * | 2017-11-27 | 2019-06-04 | 中国科学院大连化学物理研究所 | A kind of photo-ionisation and chemi-ionization source of combined ions |
| CN111199862A (en) * | 2018-11-20 | 2020-05-26 | 中国科学院大连化学物理研究所 | Capillary micro-area ionization source |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN103854952A (en) * | 2012-11-30 | 2014-06-11 | 中国科学院大连化学物理研究所 | Mass spectrum vacuum ultraviolet ionization source based on optical-window-free gas discharge lamp |
| CN108091545A (en) * | 2016-11-21 | 2018-05-29 | 中国科学院大连化学物理研究所 | A kind of ultraviolet light ionization source for mass spectral analysis |
| CN109841491A (en) * | 2017-11-27 | 2019-06-04 | 中国科学院大连化学物理研究所 | A kind of photo-ionisation and chemi-ionization source of combined ions |
| CN111199862A (en) * | 2018-11-20 | 2020-05-26 | 中国科学院大连化学物理研究所 | Capillary micro-area ionization source |
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