A kind of elemental analysis method overcoming Matrix effects in laser induced breakdown spectroscopy
Technical field
The invention belongs to Laser Plasma Emission Spectrum fields, and in particular to one kind overcomes in laser induced breakdown spectroscopy
The elemental analysis method of Matrix effects, this method can be avoided the interference of matrix element spectral line, improve laser induced breakdown spectroscopy
Detection sensitivity.
Background technique
Laser induced breakdown spectroscopy (laser-induced breakdown spectroscopy, abbreviation LIBS), is one
Kind Atomic Emission Spectral Analysis technology.The basic principle is that first going out plasma in sample to be tested ablated surface with pulse laser beam
Body obtains the type and content information of contained element in sample by collecting and analyzing the emission spectrum of Elements Atom to be measured.By
Have the characteristics that multielement analysis, quick, real-time, online, remote analysis in laser induced breakdown spectroscopy, continues for many years
Extensive concern by domestic and international researcher.
Resonant excitation laser induced breakdown spectroscopy (LIBS assisted with laser-induced
Fluorescence, abbreviation LIBS-LIF) it is that addition tunable wavelength laser is defeated on the basis of laser induced breakdown spectroscopy
The laser of specific wavelength focuses on Plasma Center out.Its core is to utilize Wavelength tunable laser by optical maser wavelength tune
Section is the resonance line wavelength of Elements Atom to be measured.Elements Atom to be measured absorbs laser energy and stimulated absorption transition occurs, then
Emit characteristic fluorescence spectrum, increases substantially the sensitivity of laser induced breakdown spectroscopy.Ideally, Elements Atom to be measured
Excitation wavelength does not have other elements atomic spectral line nearby, and laser energy is only absorbed by Elements Atom to be measured, tunable wave length laser
The utilization rate highest of energy.But in practical applications, the excitation wavelength of Elements Atom to be measured usually not can avoid base nearby
The presence of body spectral line, and the quantity of matrix element atom is far longer than Elements Atom to be measured.This causes matrix element atom big
Amount absorbs laser energy, not only reduces the utilization rate of tunable wave length laser energy, reduces Elements Atom resonant excitation effect to be measured
Rate, and matrix element atom is enhanced, so that Matrix effects are more serious.Therefore, disclosed LIBS-LIF domestic and international at present
Detection research, which is all confined to excitation line, does not have the case where matrix spectral line interference, limits the development and popularization of LIBS-LIF technology.
Since there are drawbacks described above and deficiency, this field needs to make and further improve, a kind of element is designed
Analysis method can avoid interference of the matrix element spectrum for the spectrum of Elements Atom to be measured in plasma, improve
Sensitivity when laser induced breakdown spectroscopy detects.
Summary of the invention
Aiming at the above defects or improvement requirements of the prior art, the invention proposes one kind to overcome laser induced breakdown spectroscopy
The elemental analysis method of middle Matrix effects adds two-dimentional shifting at the tunable wave length laser condensing lens in traditional LIBS-LIF system
Dynamic platform realizes that position of the tunable wave length laser spot on plasma is adjustable, quickly determines the best of Elements Atom to be measured
Excitation area, since tunable wave length laser focuses on the interference of plasma center bring matrix element.This method improves
The utilization rate of tunable wave length laser energy, improves to Elements Atom resonant excitation efficiency to be measured, improves induced with laser
The detection sensitivity of breakdown spectral.
To achieve the above object, according to one aspect of the present invention, one kind is provided to overcome in laser induced breakdown spectroscopy
The elemental analysis method of Matrix effects, which is characterized in that specifically includes the following steps:
S1. sample to be tested is got out, laser with fixed wavelength outgoing laser beam is opened, using laser beam ablation sample to be tested
Surface generates plasma;
S2. prepare a Wavelength tunable laser, the focus lamp of the Wavelength tunable laser can move up and down
It is dynamic;The Wavelength tunable laser is opened, is, output identical as the excitation line of Elements Atom to be measured by the wavelength regulation of laser beam
Laser beam and by focus lamp by laser beam focus on plasma;
S3. the focus lamp for passing through adjusting wavelength tunable laser, changes the coke of the laser beam of Wavelength tunable laser
Position of the point on plasma, acquires the plasma emission spectroscopy of different focal positions, record matrix element spectral line and
Element spectral line intensity to be measured;
S4. spectral intensity when each focal position is compared, determines the best launching efficiency region of Elements Atom to be measured, is adjusted
The position for saving tunable wave length wavelength laser focus lamp, enables the laser beam focus of tunable wave length laser in the best of plasma
On launching efficiency region;
S5. the plasma emission spectroscopy on best launching efficiency region is acquired, the plasma emission spectroscopy pair is passed through
Element to be measured carries out quantitative or qualitative analysis.
It is further preferred that in step s 2, by the way that one is arranged on the focus lamp of the Wavelength tunable laser
Two-dimensional movement platform realizes moving up and down for focus lamp.Add two-dimensional movement at the focus lamp of Wavelength tunable laser
It is adjustable to can be realized position of the focus of tunable wave length laser beam on plasma for platform, to quickly determine element to be measured
The best excitation area of atom.
Preferably, in step s3, the two-dimensional movement platform is connect with computer, two-dimensional movement is controlled by computer
The movement of platform realizes automatically scanning of the laser beam of Wavelength tunable laser on plasma, acquires different focal positions
The plasma emission spectroscopy at place.
Preferably, in step s 4, the plasma emission spectroscopy of different focal positions is collected using computer, automatically
Determine best excitation area, and it is mobile to control the two-dimensional movement platform, by the laser beam focus of tunable wave length laser wait from
The best launching efficiency region of daughter.The electronic two-dimensional movement for adding computer to control at the focus lamp of Wavelength tunable laser
Platform can be realized position automatically scanning of the focus of tunable wave length laser beam on plasma, thus rapidly automatic true
The best excitation area of fixed Elements Atom to be measured.
It is further preferred that in step s3, using Plasma Center as coordinate axis origin, coordinate system is established, by wavelength
The focal position of the laser beam of tunable laser is demarcated on coordinate system, obtains the exact position focused every time.It is more
Comparative test show to determine focal position in a manner of establishing coordinate system, the position of different focus points can be accurately determined
It sets, after being compared to wave spectrum, rapidly and accurately by the center adjustment of laser beam to best launching efficiency region.
In general, through the invention it is contemplated above technical scheme is compared with the prior art, have the following advantages that and
The utility model has the advantages that
(1) methods of Matrix effects in laser induced breakdown spectroscopy is overcome in the present invention, by Wavelength tunable on abandoning tradition
Humorous laser focuses on the way of Plasma Center, and the position of tunable wave length laser focus point is controlled by mobile focus lamp,
The different parts of scan plasma determine the lesser excitation area of Matrix effects, and for Matrix effects in the plasma
Lesser region is excited, and plasma emission spectroscopy is then acquired.This method plasma carries out the resonance of selectivity
Excitation, can reduce the absorption of matrix element atom pair tunable wave length laser energy, improve the utilization rate of laser energy, improve
To the efficiency of Elements Atom resonant excitation to be measured, enhance Elements Atom intensity of emission spectra to be measured, improves laser-induced breakdown light
The detection sensitivity of spectral technology.
(2) since matrix element atom is concentrated mainly on Plasma Center areas adjacent, the method for the present invention and tradition
The method for focusing the tunable laser heart in the plasma in LIBS-LIF is compared, can be to avoid the base of excitation Plasma Center
The absorption of matrix element atom pair tunable wave length laser is reduced in element of volume atom accumulation regions.
(3) during abducent from center, each atom number density gradually reduces plasma, and atomicity is close
Degree is too small to reduce launching efficiency, and the method for the present invention at focus lamp by being arranged two-dimensional movement platform, the difference of plasma
The scanning at position can quickly determine the highest region of launching efficiency.
(4) the method for the present invention step is simple, easily operated, and changes to optical path smaller, it is easy to accomplish, cost is relatively low, fits
It closes and promotes.
Detailed description of the invention
Fig. 1 is the flow diagram for overcoming the method for Matrix effects in laser induced breakdown spectroscopy of the invention;
Fig. 2 is the iron matrix atom spectrum intensity map that plasma different location is excited in the embodiment of the present invention 1.
Fig. 3 is the elemental chromium atom spectrum intensity map to be measured that plasma different location is excited in the embodiment of the present invention 1.
Fig. 4 is that the trace chromium of launching efficiency highest zone and excitation Plasma Center is quantitative in the embodiment of the present invention 1
Analyze comparative result figure.
Fig. 5 is the iron matrix atom spectrum intensity map that plasma different location is excited in the embodiment of the present invention 2.
Fig. 6 is the elemental nickel atom spectrum intensity map to be measured that plasma different location is excited in the embodiment of the present invention 2.
Fig. 7 is that the micro-nickel of launching efficiency highest zone and excitation Plasma Center is quantitative in the embodiment of the present invention 2
Analyze comparative result figure.
Specific embodiment
In order to make the objectives, technical solutions, and advantages of the present invention clearer, with reference to the accompanying drawings and embodiments, right
The present invention is further elaborated.It should be appreciated that the specific embodiments described herein are merely illustrative of the present invention, and
It is not used in the restriction present invention.As long as in addition, technical characteristic involved in the various embodiments of the present invention described below
Not constituting a conflict with each other can be combined with each other.
Fig. 1 is the process signal for overcoming the elemental analysis method of Matrix effects in laser induced breakdown spectroscopy of the invention
Figure;As shown in Figure 1, this method specifically includes the following steps:
S1. sample to be tested is got out, laser with fixed wavelength outgoing laser beam is opened, using laser beam ablation sample to be tested
Surface generates plasma;
S2. prepare a Wavelength tunable laser, the focus lamp of the Wavelength tunable laser can move up and down
It is dynamic;The Wavelength tunable laser is opened, is, output identical as the excitation line of Elements Atom to be measured by the wavelength regulation of laser beam
Laser beam and by focus lamp by laser beam focus on plasma;
S3. the focus lamp for passing through adjusting wavelength tunable laser, changes the coke of the laser beam of Wavelength tunable laser
Position of the point on plasma, acquires the plasma emission spectroscopy of different focal positions, record matrix element spectral line and
Element spectral line intensity to be measured;
S4. spectral intensity when each focal position is compared, determines the best launching efficiency region of Elements Atom to be measured, is adjusted
The position for saving tunable wave length wavelength laser focus lamp, enables the laser beam focus of tunable wave length laser in the best of plasma
On launching efficiency region;
S5. the plasma emission spectroscopy on best launching efficiency region is acquired, the plasma emission spectroscopy pair is passed through
Element to be measured carries out quantitative or qualitative analysis.
In a preferred embodiment of the invention, in step s 2, by the poly- of the Wavelength tunable laser
One two-dimensional movement platform is set on burnt mirror to realize moving up and down for focus lamp.
In another preferred embodiment of the invention, in step s3, the two-dimensional movement platform is connect with computer,
The movement that two-dimensional movement platform is controlled by computer, realizes that the laser beam of Wavelength tunable laser is automatic on plasma
Scanning, acquires the plasma emission spectroscopy of different focal positions.
In another preferred embodiment of the invention, in step s 4, different focal positions are collected using computer
Plasma emission spectroscopy, automatically determine best excitation area and to control the two-dimensional movement platform mobile, by tunable wave length
The laser beam focus of laser is in the best launching efficiency region of plasma.Plasma optical emission is acquired by using computer
Spectrum and control two-dimensional movement platform movement, can rapidly and accurately determine best excitation area, obtain best excitation area etc.
Ion emission spectroscopy.
In another preferred embodiment of the invention, in step s3, it using Plasma Center as coordinate axis origin, builds
Vertical coordinate system, the focal position of the laser beam of Wavelength tunable laser is demarcated on coordinate system, is obtained and is focused every time
Exact position.
Preferably to explain the present invention, two specific embodiments given below:
Embodiment 1
For detecting the trace chromium in steel, this method is described in detail.
22 steel samples of content are chosen, chromium content is from 0.0015-0.8wt% etc..
By Wavelength tunable laser wavelength regulation be equal to chromium atom resonance line Cr I 357.87nm at, in the wavelength
Near, there is iron matrix atomic spectral line Fe I 358.12nm, iron atom number is much larger than chromium atom number at the heart in the plasma.It passes
Iron atom absorbs a large amount of tunable wave length laser energies in the LIBS-LIF of system, reduces to chromium atom resonant excitation efficiency.
(1) laser with fixed wavelength outgoing laser beam is opened, ablation steel samples surface to be measured generates plasma;
(2) Wavelength tunable laser is opened, output wavelength is equal to the laser beam of Elements Atom resonance line to be measured, by poly-
Burnt mirror focuses on plasma;
(3) plasma emission spectroscopy is acquired, iron matrix atomic spectral line and chromium atom the intensity of spectral line are recorded;
(4) adjusting wavelength tunable wavelength laser condensing lens change position of the focus on plasma, and repeat 1-
3 steps,;
(5) using Plasma Center as coordinate axis origin (0mm, 0mm), in conjunction with each focal position coordinate information and siderochrome
Spectral intensity, obtain excitation plasma different location iron atom spectral intensity figure (such as Fig. 2) and chromium atom spectral intensity
Scheme (such as Fig. 3).When tunable wave length laser focus point is that Plasma Center (0mm, 0mm) is put, iron atom spectrum is most strong.And
Plasma Center chromium spectrum point of maximum intensity is appeared in when tunable wave length laser focus point is at position (0.25mm, 1.25mm).
Adjusting wavelength tunable wavelength laser condensing lens enable tunable wave length laser focus at position (0.25mm, 1.25mm);
(6) plasma emission spectroscopy is acquired, 22 steel samples production concentration of duplicate measurements and spectral intensity relationship are bent
Line (such as Fig. 4);
Available from the concentration and spectral intensity relation curve of Fig. 4, tunable wave length wavelength laser focuses on position
(0.25mm, 1.25mm) possesses higher detection sensitivity than traditional Plasma Center (0mm, 0mm) that focuses on.
In conclusion Matrix effects in laser induced breakdown spectroscopy can be overcome significantly using method of the invention, mention
The detection sensitivity of micro addition chromium in high laser induced breakdown spectroscopy detection steel.
Embodiment 2
For detecting the micro-nickel in steel, this method is described in detail.
22 steel samples of content are chosen, nickel content is from 0.002-0.513wt% etc..
By Wavelength tunable laser wavelength regulation be equal to nickle atom resonance line Ni I 318.34nm at, in the wavelength
Near, there is iron matrix atomic spectral line Fe I 318.49nm, iron atom number is much larger than nickle atom number at the heart in the plasma.It passes
In the LIBS-LIF of system, iron atom absorbs a large amount of tunable wave length laser energies, reduces to nickle atom resonant excitation efficiency.
(1) laser with fixed wavelength outgoing laser beam is opened, ablation steel samples surface to be measured generates plasma;
(2) Wavelength tunable laser is opened, output wavelength is equal to the laser beam of Elements Atom resonance line to be measured, by poly-
Burnt mirror focuses on plasma;
(3) plasma emission spectroscopy is acquired, iron matrix atomic spectral line and nickle atom the intensity of spectral line are recorded;
(4) adjusting wavelength tunable wavelength laser condensing lens change position of the focus on plasma, and repeat 1-
3 steps,;
(5) using Plasma Center as coordinate axis origin (0,0), in conjunction with the light of each focal position coordinate information and iron nickel
Spectral intensity, the iron atom spectral intensity figure (such as Fig. 5) and nickle atom spectral intensity figure for obtaining excitation plasma different location are (such as
Fig. 6).When tunable wave length laser focus point is that Plasma Center (0,0) is put, iron atom spectrum is most strong.And plasma
Center nickel spectrum point of maximum intensity is appeared in when tunable wave length laser focus point is at position (0.75mm, 0mm).Adjusting wavelength is adjustable
Resonance wave length laser condensing lens enable tunable wave length laser focus at position (0.75mm, 0mm);
(6) plasma emission spectroscopy is acquired, 22 steel samples production concentration of duplicate measurements and spectral intensity relationship are bent
Line (such as Fig. 7);
Available from the concentration and spectral intensity relation curve of Fig. 7, tunable wave length wavelength laser focuses on position
(0.75mm, 0mm) possesses higher detection sensitivity than traditional Plasma Center (0mm, 0mm) that focuses on.
In conclusion Matrix effects in laser induced breakdown spectroscopy can be overcome significantly using method of the invention, mention
The detection sensitivity of micro nickel element in high laser induced breakdown spectroscopy detection steel.
As it will be easily appreciated by one skilled in the art that the foregoing is merely illustrative of the preferred embodiments of the present invention, not to
The limitation present invention, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should all include
Within protection scope of the present invention.