JPH0875651A - Method for emission spectrochemical analysis by laser - Google Patents

Abstract

PURPOSE: To make improvements in the limit of detection and the accuracy of detection by a method wherein a laser light for excitation having a wavelength coinciding with the absorption wavelength of an element to be measured is applied to plasma produced by laser light irradiation. CONSTITUTION: When a pulse laser 1 for producing plasma is started, a pulse laser light 100 for producing plasma is oscillated 1a and an electric signal showing the oscillation is transmitted 1b to a delay circuit 5. The laser light 100 is converged 12 on the surface of a sample 6 and produces the plasma from a part of the surface of the sample 6. After a set delay time passes from this time point, the circuit 5 sends an electric signal to a photodetector 4 and a wavelength-variable laser 2 for excitation. The laser 2 oscillates a pulse laser light 200 for excitation having a wavelength coinciding with the absorption wavelength of an element to be measured and applies it to the plasma on the surface of the sample 6 so that the element to be measured in the plasma be further excited. The fluorescence emitted by this element is dispersed by a spectroscope 3 and the detector 4 detects this and outputs electric information on the spectrum. Based on this information, the intensity of emission of the element and the concentration thereof in the sample 6 are calculated 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser emission spectroscopic analysis method to which a laser induced fluorescence method is applied.

[0002]

2. Description of the Related Art With the advance of laser technology in recent years, attempts have been made in various fields to utilize it as an excitation source for spectroscopic analysis. When the surface of the sample is irradiated with a powerful laser beam focused by a condenser lens having an appropriate focal length, the surface layer is rapidly heated. In particular, when the laser light is pulsed for several tens of ns, energy is locally injected before heat is diffused into the sample, and melting and evaporation occur. The vapor is further excited by laser light to be turned into plasma and emit light. The light emitted from this plasma is transmitted to a spectroscope using an appropriate light introduction system, separated into spectra by a diffraction grating, etc., and then detected by a photographic film, photomultiplier tube, photodiode, etc. The laser emission spectroscopic analysis method is used to examine the content of the target element. Since this laser emission spectroscopic analysis method can analyze a non-conductor or a high temperature measurement object, that is, a molten material,
It is applied to direct analysis of slag.

The laser emission spectroscopic analysis method includes a single-stage excitation method using a single laser light source as an excitation source for a sample to be measured (for example, JP-A-57-100323) and a multi-stage excitation method using a plurality of laser light sources (for example, JP-A-62-188919
There are two methods. Of these, the multi-stage excitation method is an excitation method consisting of the following two stages. That is,
First, a sample surface is irradiated with a laser light pulse collected from a first laser light source to excite contained elements (atoms), and plasma is formed on the sample surface. Next, after a lapse of a predetermined time, the plasma is irradiated with a laser light pulse from the second laser light source to further excite the contained element (atoms) which has been turned into plasma.

The multi-step excitation method disclosed in JP-A-62-188919 can excite the contained element (atom) more efficiently than the single-step excitation method, and is unique to the long wavelength of the atom. It is an invention made by experimentally confirming that the emission intensity of the line spectrum can be enhanced.
Thus, by measuring the emission intensity of the eigenline spectrum at a long wavelength, laser emission spectroscopy of P, C, S, Sn, etc. becomes possible without using the emission spectrum in the vacuum ultraviolet region. The detection sensitivity and analysis accuracy in the analysis are improved.

[0005]

In the above-mentioned conventional laser emission spectroscopic analysis method, the atoms to be measured are thermally excited. Therefore, in order to excite many atoms to be measured and increase the emission intensity thereof. , It is necessary to form a high temperature plasma. However, since hot plasma emits a large amount of continuous light,
When high-temperature plasma is formed, the background of the measurement signal becomes high and the S / N ratio decreases.
In particular, in the (extremely) low concentration region, this background fluctuation cannot be ignored and the measurement error increases. Also,
In the high temperature plasma, elements other than the element to be analyzed are also excited and emit light. For this reason, when measuring trace elements in steel, the emission of the atoms to be measured is hampered by the emission of iron, which is the main component in the steel, and some elements are analyzed by spectroscopic analysis in the vacuum ultraviolet region. If you do not take a method such as separating the emission of iron with a spectrometer with high resolution to analyze it, obtain sufficient accuracy in the low concentration range of several ppm to several tens of ppm by elemental analysis in steel. Is difficult. Light emitted from the vacuum ultraviolet region around 200 nm has a low transmittance through the optical fiber, which makes it difficult to transmit a light emission signal through the optical fiber. Further, in order to increase the resolution, a long optical path is required to disperse the light, and the spectroscope itself becomes large. These are obstacles to the online application of the laser emission spectroscopy.

The present invention has been made in view of the above problems, and a laser-induced fluorescence method is applied to a conventional laser emission spectroscopic analysis method to selectively select an element to be analyzed by laser light absorption in low-temperature plasma. It is an object of the present invention to provide a laser emission spectroscopic analysis method that can be excited to prevent interference of the light emission of the main component element and improve detection limit and detection accuracy. In addition, because the element to be analyzed selectively emits light, there is no interference of the emission of the main component, so the resolution of the spectroscope may be low, and the emission in the long wavelength range, which cannot be used for analysis by conventional methods, is possible. It is an object of the present invention to provide a laser emission spectral analysis method capable of performing analysis.

Further, by making the wavelength of the excitation laser light and the measured fluorescence wavelength different from each other, it is possible to prevent the stray light of the excitation laser light from interfering with the surface of the object to be measured, and to perform highly accurate analysis. It is an object of the present invention to provide a laser emission spectral analysis method capable of performing the above. In addition, it is possible to make the optical axes of the laser light for atomization and the laser light for excitation coaxial, which simplifies the device configuration and expands the online application, and melts molten steel. When analyzing things,
It is an object of the present invention to provide a laser emission spectroscopic analysis method which can minimize the influence of fluctuations in the melt surface and can perform highly accurate analysis.

[0008]

In order to achieve the above object, a laser emission spectral analysis method (1) according to the present invention is directed to irradiating a surface of a measuring object with a laser beam for plasma generation and measuring the surface of the measuring object. In the laser emission spectroscopic analysis method in which the part is made into plasma and the light emitted from the plasma is spectrally analyzed, the plasma generated by the laser light irradiation is irradiated with excitation laser light having a wavelength that matches one of the absorption wavelengths of the element to be measured. It is characterized in that the atomic fluorescence obtained by the above is analyzed spectroscopically.

A laser emission spectroscopic analysis method (2) according to the present invention is the same as the laser emission spectroscopic analysis method (1).
The wavelength of the excitation laser light and the wavelength of the measured atomic fluorescence are different from each other.

The laser emission spectral analysis method (3) according to the present invention is the same as the laser emission spectral analysis method (2), except that the laser light for plasma generation and the laser light for excitation are in the same direction. It is characterized by irradiating the object to be measured from.

The laser emission spectral analysis method (4) according to the present invention is the same as the laser emission spectral analysis method (1), except that 1 μs to 1 ms after irradiation with the pulsed laser beam for plasma generation.
It is characterized in that plasma generated during the passage of time is irradiated with a pulsed laser beam for excitation having a wavelength that matches one of the absorption wavelengths of the element to be measured.

[0012]

In the laser emission spectroscopic analysis method according to the above method, for example, a Q switch pulse YAG (yttrium-al) is used as a plasma conversion laser for converting the sample to be measured into plasma.
uminum-garnet) laser or the like is used. The principle of the laser emission spectral analysis method according to the above method will be described below with reference to FIG. FIG. 1 (a) is a schematic diagram showing the principle of the laser emission spectral analysis method according to the above method, and FIG. 1 (b) is a schematic diagram showing the mechanism by which fluorescence is generated by the excitation laser light. Is.

The laser light for plasma conversion is condensed on the surface of the object 6 to be measured, and a part of the object 6 to be measured is turned into plasma. When the generated plasma 30 is irradiated with the excitation laser light 20 having a wavelength that matches one of the absorption wavelengths of the atoms to be measured, the laser energy is selectively absorbed by the atoms to be measured. That is, the atoms to be measured in the lower level (1) 50 are excited to the upper level 70 by the excitation laser light 20. Several kinds of atomic fluorescence are emitted when the atoms excited by the upper level 70 transit to the lower level again. This atomic fluorescence is fluorescence 40 having a wavelength that coincides with the laser light for excitation emitted when transiting to the original lower level (1) 50.
And the excitation laser light emitted at the time of transition to another lower level (2) 60 and the fluorescence 41 having a different wavelength. As the excitation laser light source, a wavelength tunable laser is preferable because it is necessary to irradiate laser light having a wavelength matching the absorption wavelength of the element to be measured. Further, since the atomic fluorescence is observed during the irradiation of the excitation laser light 20, the SN is adjusted by synchronizing the detector for detecting the atomic fluorescence with the excitation laser.
It is possible to improve the ratio. Rays related to the above method
In the emission spectroscopy analysis method, the atomic fluorescence 40 or 41 is used.
Are spectroscopically analyzed.

By the method of spectroscopically analyzing the atomic fluorescence 41 having a wavelength different from that of the exciting laser light 20, the scattered light and the reflected light of the exciting laser light 20 from the object 6 to be measured become the fluorescent light to be measured. It is possible to prevent interference. When this method is used, the optical axis of the laser light for plasma generation and the optical axis of the laser light for excitation 20 are made coaxial, and the laser light for plasma generation and the laser light for excitation 20 are the same. It is possible to realize a laser emission spectral analysis method of irradiating from the direction. Hereinafter, this system will be referred to as a coaxial system. This coaxial system needs only one irradiation direction of laser light, which simplifies the device configuration. This expands the practical online application.
Further, since there is no interference of the excitation laser light 20, it is possible to measure pure fluorescence intensity, which leads to higher accuracy of analysis.

When irradiating the plasmaizing laser and the exciting laser from different directions when analyzing a molten material such as molten steel, if the surface of the molten material changes, the exciting laser light Two
The position irradiated with zero plasma 30 changes according to the shake of the melt surface. Therefore, a measurement error occurs. In the coaxial system, the excitation radiation is always
Since the light 20 is applied to the same position in the plasma 30, it is possible to minimize the measurement error due to the fluctuation of the melt surface.

The excitation laser light source is not required to have a variable wavelength, but may output a wavelength matching the excitation energy of the element to be measured. For example, when the element to be measured is C, the ArF excitation wavelength of 193.1 nm of the excimer laser can be used.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the laser emission spectral analysis method according to the present invention will be described below with reference to the drawings. FIG. 2 is a block diagram schematically showing an example of an emission spectroscopic analysis apparatus for carrying out the laser emission spectroscopic analysis method according to the first embodiment of the present invention. It should be noted that in FIG. 2, the arrow indicated by the alternate long and short dash line indicates the flow of the electric signal, and the arrow indicated by the solid line indicates the flow of the laser light.

In the figure, 6 indicates a sample, and 1 indicates a pulsed laser for plasma generation for forming plasma on the surface of the sample 6. The plasma laser pulse laser 1 is formed with a pulse laser output terminal 1a and an electric signal output terminal 1b, and the electric signal output terminal 1b is connected to the delay circuit 5. The pulsed laser light 100 for plasma generation is output from the pulse laser output terminal 1a, and the pulsed laser light 100 for plasma generation is passed through the mirror 9, the condenser lens 12 and the perforated mirror 10 to the surface of the sample 6. It is designed to be illuminated.

One output terminal 5a of the delay circuit 5 is connected to the excitation wavelength tunable laser 2 for further exciting the atoms to be measured in the plasma, and the other output terminal 5b is connected to the photodetector 4. Has been done. The pumping wavelength tunable laser 2 outputs the pumping pulse laser light 200 having a wavelength matching the absorption wavelength of the element to be measured, and the pumping pulse laser light 2
00 is radiated to the plasma formed on the surface of the sample 6 through the prism 7 and the prism 8. Further, the fluorescence emitted from the plasma is reflected by the perforated mirror 10 and then condensed by the condenser lens 11 to be input to the spectroscope 3. Spectroscope 3
The photodetector 4 is connected to the computer, and the photodetector 4 is connected to the computer 13. Although not shown, the pulsed laser 1 for plasma generation, the wavelength tunable laser 2 for excitation, and the delay circuit 5 are connected to the computer 13 and connected to the computer 13.
It is controlled by the controller 13.

The plasmaization pulse laser 1 has an output of 0.5 J / P or less and a pulse width of 20 ns.
Then, a Q switch YAG laser having a wavelength of 1,064 nm was used. Further, as the wavelength tunable laser 2 for excitation, the output is several mJ / P, the pulse width is 20 ns, the wavelength tunable region is the second harmonic of the dye laser having a wavelength tunable range of 400 to 1000 nm, and the wavelength tunable range is 205 to 400 nm. I used the one.

Next, the operation of the emission spectroscopic analyzer constructed as described above will be described with reference to FIG. FIG. 3 is a flow chart showing the operation of the computer 13.
First, in step 1, measurement conditions are set. That is, setting of the wavelength of the excitation pulse laser light 200 output from the excitation wavelength tunable laser 2 according to the element to be measured,
Also, the delay time is set in the delay circuit 5.
When the setting is performed and the plasma laser pulse laser 1 is activated by the computer 13, the following operation is executed.

The pulse rate of the pulsed laser 1 for plasma generation
Pulse laser light 100 for plasma generation from the laser output terminal 1a
When the laser pulse is oscillated, at the same time, the pulsed laser light 10 for plasma generation is transmitted from the electric signal output terminal 1b to the delay circuit 5.
An electric signal indicating that 0 is oscillated is transmitted. The pulsed laser light 100 for plasma generation is reflected at a right angle by the mirror 9, and is condensed on the surface of the sample 6 through the condenser lens 12 with a beam diameter of 0.1 mm to 2.0 mm. When the pulsed laser light 100 for plasma conversion is irradiated, a part of the surface of the sample 6 is converted into plasma.

At a time of 1 μs to 1 ms from the time of irradiation with the plasmaizing pulsed laser light 100 for forming plasma on the surface of the sample 6, at a time when a predetermined time corresponding to the atom to be measured has elapsed. In other words, when the delay time set in step 1 elapses from the time when the pulsed laser light 100 for plasma generation is irradiated, an electric signal is sent from the delay circuit 5 to the photodetector 4 and the wavelength tunable laser 2 for excitation. Transmitted. When the electric signal is received, the excitation wavelength tunable laser 2 oscillates the excitation pulse laser light 200 having a wavelength matching the absorption wavelength of the element to be measured according to the measurement conditions set in step 1. Excitation pulse ray
The optical path of the light 200 is changed by the prism 7 and the prism 8, and the plasma on the surface of the sample 6 to be measured is irradiated.
As a result, the element to be measured in the plasma is further excited. Then, the fluorescence emitted from the element to be measured is reflected by the perforated mirror 10 and is dispersed by the spectroscope 3 through the condenser lens 11. The dispersed light is detected by the photodetector 4, and the electrical information of the spectrum is stored in the computer 1.
Sent to 3.

In step 2, the emission intensity of the element to be analyzed is calculated based on the electric information of the spectrum received from the photodetector 4. Next, in step 3, the calibration curve is applied to the calculated emission intensity to calculate the concentration of the element to be measured in the sample 6. Finally, the density calculated in step 4 is output.

The concentration of Si contained in the low alloy steel was measured by an apparatus using the laser emission spectral analysis method according to the example.
The spectrum at that time is shown in FIG. For comparison, FIG. 5 shows a spectrum measured by a conventional laser emission spectroscopic analysis method using a thermal excitation method using high-temperature plasma. 4 and 5, the horizontal axis represents wavelength (Å) and the vertical axis represents emission intensity (count number).

As is clear from comparing FIGS. 4 and 5, the laser emission spectrum analysis method according to the embodiment is different from the conventional laser emission spectrum analysis method in the Si spectrum and the background. The ratio is increasing. Further, since the plasma is thermally excited in the conventional laser emission spectral analysis method, many elements are excited at the same time, and it is impossible to excite only the measurement target element. In fact, many Fe spectra are observed in the spectrum shown in FIG. 5, and the Si spectra cannot be identified due to interference with the Fe spectra. However, in the measurement by the laser emission spectroscopic analysis method according to the example, only Si atoms are selectively excited to emit fluorescence, so that interference of Fe spectrum is significantly reduced. In addition, the Si spectrum intensity is also improved as compared with the conventional one. As you can see from these things,
When the measurement is performed using the laser emission spectroscopic analysis method according to the example, the SN ratio of the spectrum signal in the element to be measured (Si) can be significantly improved as compared with the conventional analysis method, and in the emission spectroscopic analysis. The detection limit and detection accuracy can be significantly improved.

FIG. 6A shows a delay time (horizontal axis, μsec) from irradiation of the pulsed laser light 100 for plasma generation to irradiation of the pulsed laser light 200 for excitation and Si spectrum intensity (vertical axis, It is a graph showing the relationship with the number of counts. The measurement is performed in two ways, an Ar atmosphere and an air atmosphere. Further, FIG. 6B is a graph showing the relationship between the delay time (horizontal axis, μsec) and the P spectrum intensity (vertical axis, count number) in the Ar atmosphere.
In the graphs shown in FIGS. 6A and 6B, the irradiation of the excitation pulsed laser light 200 indicates that the pulsed laser light for plasma 1
It is shown that fluorescence can be observed when 1 μsec to 1 msec elapses after 00 irradiation.

In the above embodiment, the optical axis of the excitation pulse laser beam 200 may be the same as or different from the optical axis of the plasma conversion pulse laser beam 100. Further, as the light source of the excitation pulse laser light 200, it is sufficient that laser light having a wavelength matching the excitation energy of the element to be measured can be output. Therefore, the excitation wavelength tunable laser 2 as in the embodiment is used. You don't have to use it. For example, when the element to be measured is C, the wavelength is 193.1 nm.
Excimer laser can be used.

Next, a laser emission spectral analysis method according to Example 2 of the present invention will be described. FIG. 7 is a block diagram schematically showing a coaxial laser emission spectroscopic analysis apparatus for carrying out the coaxial laser emission spectroscopic analysis method according to the second embodiment. In FIG. 7, 1 is a pulse laser for plasma generation,
2 is a wavelength tunable laser for excitation, 3 is a spectroscope, 4 is a photodetector, 5 is a delay circuit, 6 is a sample, 13 is a computer, 1
Reference numeral 0 is a perforated mirror, 11 is a condenser lens, 12 is a condenser lens, 21 is a mirror, and 22 is a dichroic mirror.

The dichroic mirror-22 is an ultraviolet light 200.
nm-400 nm is transmitted, but YAG laser light (1
064 nm) is a mirror that reflects light. Computer 1
The processing contents of No. 3 are as shown in the flowchart shown in FIG. Compared with the emission spectroscopic analysis apparatus according to the first embodiment shown in FIG. 2, in the emission spectroscopic analysis apparatus according to the second embodiment shown in FIG. 7, a pulsed laser light for plasma generation is generated by the dichroic mirror 22. The difference is that 100 and the excitation pulse laser light 200 are coaxially overlapped.

The results of measuring P in steel by the emission spectroscopic analyzer configured as described above are shown below. First, FIG. 8 shows the energy level of P to which the emission spectroscopic analysis method according to Example 2 can be applied. As can be seen from FIG. 8, P
At 254 nm when excited near 254 nm
Atomic fluorescence is observed in the vicinity and around 214 nm. Therefore, the spectrum of P atom fluorescence around 254 nm when excited at 254 nm is shown in FIG.
FIG. 10 shows a spectrum obtained by measuring P atom fluorescence in the vicinity. 9 and 10, the horizontal axis represents wavelength (Å) and the vertical axis represents emission intensity (count number).

As shown in FIG. 9, a very large signal can be observed in the vicinity where P atomic fluorescence (atomic fluorescence having the same wavelength as that of the excitation pulsed laser light 200) is observed. This is mainly the sample 6 of the pulsed laser light 200 for excitation.
This is due to scattered light and reflected light from the surface. In this case, it is impossible to distinguish P atom fluorescence proportional to the P element concentration from the scattered light and the reflected light.

On the other hand, in the case of FIG. 10, since the wavelength of the excitation pulse laser light 200 (254 nm) and the wavelength of the measured fluorescence (around 214 nm) are different,
Pure P fluorescence intensity can be measured without scattered light of the excitation pulse laser light 200 from the surface of the sample 6. That is, if the analysis method according to the second embodiment is used, it is possible to enable emission spectral analysis in a coaxial system.

As described above, when the emission spectral analysis method according to the second embodiment is used, the wavelength of the excitation pulse laser light 200 and the wavelength of the measured fluorescence are different,
It is possible to prevent interference due to scattered light and reflected light of the excitation pulse laser light 200 from the surface of the sample 6 which is the measurement object. As a result, the pulsed laser light 100 for plasma conversion is used.
The optical axis of and the optical axis of the excitation pulse laser light 200 can be made coaxial, and the device configuration can be simplified and since there is no scattered light, pure fluorescence intensity can be measured. Highly accurate emission spectroscopic analysis can be performed.

[0035]

According to the laser emission spectral analysis method (1) of the present invention, the excitation laser having a wavelength corresponding to any of the absorption wavelengths of the element to be measured is added to the plasma generated by the laser light irradiation. -Atomic fluorescence obtained by irradiating the light is spectroscopically analyzed. That is, since only the element to be measured is selectively re-excited and emits fluorescence, interference with the spectrum of other contained elements is eliminated,
The SN ratio, which is the background ratio to the spectrum of the element to be measured, can be improved. Thereby, the detection limit and the detection accuracy in the emission spectroscopic analysis can be improved, and the analysis of the trace amount element can be performed.

Further, in the laser emission spectral analysis method (2) according to the present invention, the above laser emission spectral analysis method (1)
In, because the wavelength of the excitation laser light and the wavelength of the measurement atomic fluorescence are different wavelengths, it is possible to prevent interference due to scattered light from the measurement object surface of the excitation laser light,
The pure atomic fluorescence of the measuring element can be measured. Thereby, the detection limit and the detection accuracy in the emission spectroscopic analysis can be improved, and the analysis of the trace amount element can be performed.

Further, in the laser emission spectrum analysis method (3) according to the present invention, the above laser emission spectrum analysis method (2) is used.
In the above, since the laser light for plasma generation and the laser light for excitation are applied to the object to be measured from the same direction, the laser emission spectral analysis method (2) has the effect and
The light can be emitted in only one direction.
The emission spectroscopic analyzer can be simplified.

Further, in the laser emission spectroscopic analysis method (4) according to the present invention, the absorption wavelength of the element to be measured is absorbed in the plasma generated during 1 μs to 1 ms after the irradiation of the pulsed laser light for plasma generation. Since the excitation pulse laser light having a wavelength corresponding to any of the above, is irradiated with a pulse laser light having a wavelength corresponding to any of the absorption wavelengths of the element to be measured at a timing at which fluorescence can be reliably measured. Then, only the element to be measured can be re-excited, and the fluorescence emitted by the element to be measured can be measured without interference of the spectrum of other contained elements. As a result, SN, which is the background ratio to the spectrum of the element to be measured, is
The ratio can be improved, the detection limit and detection accuracy in the emission spectroscopic analysis can be improved, and the trace amount element can be analyzed.

[Brief description of drawings]

1A and 1B are schematic views showing the principle of a laser emission spectroscopic analysis method according to the present invention.

FIG. 2 is a block diagram schematically showing an example of a laser emission spectroscopic analysis apparatus for carrying out the laser emission spectroscopic analysis method according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing the operation of the computer.

FIG. 4 is a diagram showing a Si spectrum when the Si concentration in the low alloy steel is measured by the laser emission spectral analysis method according to the example.

FIG. 5 is a diagram showing a Si spectrum when the Si concentration in the low alloy steel is measured by a conventional laser emission spectroscopic analysis method.

FIG. 6 (a) is a graph showing the relationship between the irradiation delay time from the irradiation of the pulsed laser light for plasma generation to the irradiation of the pulsed laser light for excitation and the Si spectrum intensity. ) The figure shows the delay time and P in Ar atmosphere.
It is the graph which showed the relationship with spectrum intensity.

FIG. 7 is a block diagram schematically showing an example of a laser emission spectroscopic analysis apparatus for carrying out a laser emission spectroscopic analysis method according to a second embodiment of the present invention.

8 is a diagram showing an energy level of P used in Example 2. FIG.

FIG. 9 is a spectrum of P in the coaxial system when the P concentration in the low alloy steel is measured by a laser emission spectroscopic analysis method with the wavelength of excitation laser light and the wavelength of measured atomic fluorescence being the same. It is the figure which showed.

FIG. 10 shows a P spectrum when P concentration in a low alloy steel is measured by a laser emission spectroscopic analysis method by setting a wavelength of atomic fluorescence for measurement to a wavelength different from a wavelength of laser light for excitation. It is the figure shown.

[Explanation of symbols]

 1 Plasmaization pulse laser 2 Excitation wavelength tunable laser 5 Delay circuit 6 Sample (measurement object) 13 Computer 20 Excitation laser light 22 Dichroic mirror 30 Plasma 40, 41 Fluorescence 50 Lower level (1) 60 lower level (2) 70 upper level 100 pulsed laser light for plasma 200 pulsed laser light for excitation

Claims (4)

[Claims] 1. A laser emission spectroscopic analysis method for irradiating a surface of a measurement object with a laser beam for plasmaization to convert a part of the surface of the measurement object into a plasma and spectrally analyzing light emitted from the plasma. A laser emission spectroscopic analysis method, which comprises spectrally analyzing atomic fluorescence obtained by irradiating the plasma generated by the method with excitation laser light having a wavelength that matches one of the absorption wavelengths of the element to be measured. 2. The laser emission spectral analysis method according to claim 1, wherein the wavelengths of the excitation laser light and the measured atomic fluorescence are different from each other. 3. The emission spectroscopic analysis method according to claim 2, wherein the laser light for plasma generation and the laser light for excitation are applied to the object to be measured from the same direction. 4. 1 μm after irradiation with pulsed laser light for plasma conversion
2. The laser emission spectroscopic analysis according to claim 1, wherein the plasma generated during a period of s to 1 ms is irradiated with a pulsed laser beam for excitation having a wavelength that matches one of the absorption wavelengths of the element to be measured. Method.