SU1363034A1 - Method of spectrum analysis - Google Patents

Abstract

This invention relates to quantitative spectral analysis methods. The goal is to increase the speed, efficiency and accuracy of the spectral analysis of multicomponent gas mixtures. The method is based on a combination of diluting the analyzed mixture with helium by 5P-IOO times with the correction of the relative intensity of the lines in the analytical pair, depending on the composition and content of the third components. The correlation between this intensity and the relative intensity of the lines in fikspar takes into account the dependence of the analysis results on the composition of the sample being analyzed. The method is illustrated by the example of the determination of argon in complex mixtures of Ar-Nj-Oj-. H with an arbitrary and wide variation (from 5 to 95 mol.%) Of the concentration of each of the components. The method allows to reduce the systematic analysis errors to the level of random errors of photographic registration, i.e. about 3-4%. 3 il. & Г ™ CUBE SLE 4 ::

Description

The invention relates to the quantitative methods of spectral, mainly gas, and can be used in the analysis of gases g in metals, semiconductor samples, in determining the quantitative composition of residual gases in vacuum devices, as well as in other objects in which the elements constituting gas sample covers a wide range of concentrations.

The aim of the invention is to increase the speed, efficiency and t5 accuracy of spectral analysis of multicomponent gas mixtures.

The proposed method can be implemented for a wide range of analyzed multicomponent gas mixtures consisting of any combination of atomic (inert and molecular inorganic gases (N, 0, H2, CO, SP ,,, N0, N0, etc.), the concentration of each of which varies arbitrarily over such wide limits (almost from 300 to 0% V) that these variations have a significant effect on the conditions of excitation of spectra in the gas discharge and, therefore, on the intensity of analytical atomic lines or rn-band molecules. Identify it component: in such mixtures there can be any elements that are 35 s under normal conditions with monatomic or diatomic gases, namely, neon, argon, xenon, krypton, hydrogen, nitrogen, oxygen — as well as some so-called gaseous –40 One of the elements: sulfur, carbon, chlorine, fluorine, and t, 5 each of which are composed of many molecular gases,

20

25

thirty

Not only does it not weaken, but, despite the decrease in the concentration of anti-particulate particles per unit volume of the discharge tube, it may even increase, due to the increase in the average energy of the exciting electrons in the gas-discharge plasma as the concentration of the excitable gels increases. When the sample is diluted by helium by a factor of 10 to 10, the plasma stabilizes and the factor of decrease in the concentration of analytical particles becomes prevalent, which leads to an almost linear decrease in the intensity of the analytical lines and, consequently, to a decrease in the detectivity of the analytical technique. (A similar effect was obtained when testing the invention proposed here by diluting a multicomponent sample with helium). Further, with such small dilution rates (up to 100 times), not only real gels are detected by detectable impurities, but also the memory of the discharge tube, the idle signal of the device k, in addition, there is no difficulty in dosing the test tubes gas that occurs when it is diluted with especially pure helium by 10 10 times.

The type of non-auger communication system between the analytical and corrective signals arising from the variation; the content of the various components of the analyzed mixture is different for different combinations of analytical and correction signals and depends on the chosen dilution degree of the analyzed by helium.

Fig 1 shows an example of such links.

The analysis of the analyzed multicomponent gas mixture is carried out by a not particularly clean hetero. containing impurities of the order of 10 mol.%, and the usual

for the determination of argon at dilution ™ According to the proposed method of dilution of the analyzed mixture gel | -1em in

50-100 times. The nonlinear relationship between argon concentration, analytical and corrective signals can be obtained as a solution of a system of three equations: RBYX equations adequate to the correlation shown in Fig. 1, and a third equation adequate to the gradient shown in Fig. 2. On the fng, 1 regression line of the standard non-linear correlation condition between the analytic signal

technical helium with a total content of impurities of the order of 10 mol.%, and not by 10 0 times, but up to 100 times. The choice of such a degree of dilution (R) of the sample by helium is due to the fact that in this case the correlation bonds that are used to determine impurities in helium effectively act and the intensity of the analytical lines that determine the X elements, as a rule.

55

ZQ And the correction signal f kspara Yj, 5 free from the influence of third 0

five

50

0

five

0

Not only does it not weaken, but, despite the decrease in the concentration of anti-particulate particles per unit volume of the discharge tube, it may even increase, due to the increase in the average energy of the exciting electrons in the gas-discharge plasma as the concentration of the excitable gels increases. When the sample is diluted by helium by a factor of 10 to 10, the plasma stabilizes and the factor of decrease in the concentration of analytical particles becomes prevalent, which leads to an almost linear decrease in the intensity of the analytical lines and, consequently, to a decrease in the detectivity of the analytical technique. (A similar effect was obtained when testing the invention proposed here by diluting a multicomponent sample with helium). Further, with such small dilution rates (up to 100 times), not only real gels are detected by detectable impurities, but also the memory of the discharge tube, the idle signal of the device k, in addition, there is no difficulty in dosing the test tubes gas that occurs when it is diluted with especially pure helium by 10 10 times.

The type of non-auger communication system between the analytical and corrective signals arising from the variation; the content of the various components of the analyzed mixture is different for different combinations of analytical and correction signals and depends on the chosen dilution degree of the analyzed by helium.

Fig 1 shows an example of such links.

,

55

ZQ And with the correction signal φ xpar Yj, 5 free from the influence of the third components, is constructed by changing the concentration of the detected element argon) in two component components, composed of helium and argon, and approximated by the hyperbola equation in the form

7 - h - °

Z, b ------ ()

where a, b, d are the parameters of the hyperbola. The regression lines 1,2,3 (Fig. 1), which characterize the parallel displacement of the hyperbola from the standard MN hyperbola as other impurities are added to helium, are constructed for given concentration levels of the detected argon component in helium by changing the composition and concentration of the third components ( N, 0, Hj, etc.) and approximate them with a straight-line equation in segments as

Z - Z. A (Y-YJ

(2)

where Z and Y are distorted by the effect of the third components, the experimental values of the analytical and correction signals, respectively; A is the regression coefficient of the correlation link between Z and Y, obtained by varying the composition and concentration of the third components in the analyzed sample diluted with helium.

. The standard calibration line (Fig. 2) of the dependence of the standard analytical signal Z on the concentration of a detectable element SAg is constructed for a two-component mixture composed of a gel with additives of the argon element being analyzed and approximated by the direct equation

V-X - a „,

(3)

G.Ch. Z - corresponding to the standard condition is free from the influence of the third components of the analytical signal;

 bj, are the parameters of the equation;

X Ig SAg.

The joint solution of equations (1), (2) and (3) with respect to the concentration of the element being determined after excluding Yn and Z from them,

gives a non-linear relationship to determine the desired argon concentration in helium

if (Z-bb) -A (Y-a) X-I

L

lA lZ5lziZ-biL

Ad - a,, (4)

where X Ig SAg is a function of the concentration of the element being detected (here, argon is in helium);

Z 18 („/

 Another analytical signal for the case of determination of argon in helium;

5 Y lg (Ift, ii /

/ Iftrl) correction signal for the case of determination of argon in helium;

0 hell and b are the parameters of the standard calibration curve (Fig. 2), built for a pure two-component mixture of gels

with the element detected — argon; A is the regression coefficient of the correlation

0sv zi between anapiti

Z signal and corrective signal

signal Y, obtained by changing

5n the composition and concentration of undefined components in helium for given concentration levels

A definable element (argon) in helium; a, b, d - parameters of the regression line of standard conditions on the correlation plane,

constructed for a two component sample by varying the concentration of a certain element (argon) in helium.

The parameters of the nonlinear equation (4) a ,, b, d, and A are empirically predetermined. However, using the most undiluted analyzed multi-component gas mixture, where all or many components are present in comparable and large

concentrations, finding these parameters is not only difficult, i.e. a change in the concentration of almost any component of the mixture causes a significant change in the concentration of other components, which makes it difficult to establish correlations, but it is also impractical because the parameters found in these conditions may differ significantly from those that correspond to correlations in conditions R-fold dilution of the analyzed multicomponent gas mixture with helium, as regulated by the proposed method. Here, the finding of the above parameters of the nonlinear equation of the relationship between X, Y, Z is carried out not on the analyzed gas mixture itself, but on similar mixtures diluted by helium by R times. The optimal dilution rate of RfelOO when all the components of the mixture become small enough impurities in helium to realize strong correlations, but not so small that the installation idle signal, memory of the discharge tube and the helium gas are significant. .

The nonlinear relationship (4) relates to the measured concentration of the element to be detected in helium and, in addition, provides an accurate analysis result for the most multicomponent gas mixture for the case of arbitrarily varying concentrations of the element being determined and the third components in the irradiance interval of their change, provided that The ratio (D) additionally takes into account the degree of dilution R of the analyzed multi-gas mixture with helium:

X x) - g

(five)

where X and X are respectively the logarithms of the concentration of the element being determined in the mixture itself and in helium;

g is the logarithm of the dilution rate of the analyzed mixture with helium.

The formula (5) in combination with the nonlinear relation (4) makes it possible to obtain an exact result of determining the desired concentration of the element being determined in the analyzed multicomponent gas mixture with arbitrarily varying concentrations of the element being determined and indeterminable components in a wide range of their changes. The nonlinear relationship (5) reflects a particular case of nonlinear correlation, in which only one of these relations is nonlinear, crawled by changing the end of the measured element in the diluted helium of the analyzed mixture, and the other connection is obtained by changing the concentration of the third components — linear. In the general case, both of these connections can be non-linear (FIG. 3). In this case, the calculated non-linear formula becomes somewhat more complicated:

l:

Z +

.il§

L ° - parameters of equations

hyperbolas describing curvilinear regression lines 4,5,6 (fig.Z)

7. - “:

do

Yo lo

.i kldlz -§lt-5 i bl) lr sllxi2zbi -dy

2a

however, the set of operations during the implementation of the proposed method remains unchanged. In all cases, she vkpochaet to herself: measuring the optimal degree of dilution

R of the analyzed gas mixture helium; 3KcnepHMeHTanfjHoe the establishment of a nonlinear correlation between the X, Y

HZ in diluted helium in R times multicomponent gas mixtures, similar in composition to the analyzed; helium dilution by R times the multi-component gas mixture being analyzed; measurement of Y and Z signals in this diluted helium mixture; determining, by a predetermined non-linear relationship between X, Y and Z, the concentration of the element being detected in X in helium; calculation by the known X and Z values of the concentration of the element to be determined in the analyzed multi-component mixture.

The method is illustrated by the example of the determination of argon in a multicomponent gas mixture composed of comparable concentrations of argon, nitrogen, oxygen, hydrogen. The concentration of argon in the analyzed mixture varied from 95 to 5%. T ;; - components were present in the analyzed sample both individually and together in a concentration of from 5 to 95%. Helium was used as the diluent gas, which has the highest

 ) i2AZ21Xi2z§§) ..

0.93 I 2

 .12()-()

four

35

de X IgC is the logarithm of the concentration of the element to be determined in the analyzed multicomponent gas mixture;

g IgR is the logarithm of the dilution degree of the analyzed mixture with helium;

Z and Y - analytical and correction signals measured in a diluted helium R times the analyzed mixture;

) Y lg (.lI / lArl) 40

45

(Ifl formula

the invention

50

This is due to possible dilution with a mixture of liquidation and correction, and the correlation is corrected by correctional corrections by non-helium

A method of spectral analysis, including diluting the analyzed multicomponent gas mixture with gas, was not introduced into the discharge zone, measuring the analytical and corrective sigiu, by which the concentration of the determined elemental potential of excitation of the spectra with respect to other elements constituting the analyzed gas mixture is judged. The optimal degree of dilution of the analyzed mixture by helium, which provides strong correlations, has been established experimentally in the range from 50 to 100 times. The discharge was excited in a quartz capillary with a diameter of 2 mm with external electrodes from a high-frequency generator UVG-2 (frequency 50 MHz, power 40 W at a pressure of 690 Pa. Aril 442.6 nm and Hel 443.7 line intensities served as an analytical signal nm, and the correction signal was formed from the intensity ratio of the Aril lines at 442.6 nm and Arl 430.0 nm. The exposure time when taking spectra on a photographic plate of the Micro type with a sensitivity of 45 units on an EC11-28 spectrograph was 5 min.

The formula for calculating the content of a definable element, in this case argon, in a multicomponent gas mixture is:

0.40 + r

(7)

five

0

five

0

five

In the analyzed mixture, characterized in that, in order to increase expressivity, economy and accuracy of spectral analysis of multicomponent gas mixtures, the multicomponent gas mixture is diluted 50-100 times with traditional helium to reveal non-linear correlation links between the analytical and the corrective signals, establish on this basis a non-linear relationship between the concentration of the element being determined — the analytical and correction signals — determine the correlation coefficient of the correlation relation between analytical and corrective signals obtained by changing the composition and concentration of indeterminate components in helium to given levels of the concentration of the element being determined in helium, and the concentration of the element being studied are determined by the detected nonlinear correlation.

-cb -a, it o, g

X

 /

-0,6

ttfCtr-X

-0.6

/

{Rig.

Claims (1)

Claim' The method of spectral analysis, including diluting the analyzed multicomponent gas mixture with gas, introducing it into the discharge zone, measuring the analytical and correcting signals, which are used to judge the concentration of the element being determined and the correcting signals, establish on this basis a non-linear relationship between the concentration of the element being determined · analytical and correcting signals, determine the regression coefficient of the correlation between the analytical and correcting signals obtained by changing Nia composition and concentration of undefined components in helium to the predetermined concentration levels of the element in helium, and the revealed nonlinear relation sheniyu t-determined concentration of the test element. Figure 1 FIG. 2 1 363 034