SU1057820A1 - Nuclear fluorescence measuring method - Google Patents

Abstract

A METHOD FOR MEASURING AN ATOMIC FLUORESCENCE, which consists in irradiating atomic vapors, as an analytic cell, by pulsed resonant radiation followed by a fluorescence signal, which, in order to improve the accuracy of measurements, excites the analytical cell by pulsed resonance patterns and improves the accuracy of measurements. 78 Z.ae 2,3g 2,68; by radiation, the radiation intensity of the analytical cell is measured at two values of the intensity of the resistive: a. Excitation excitation radiation, at which the intensity ratio of the fluorescent of the measured and scattered radiations in the meas (the signal of the signal is no more than 10 times greater, the magnitude of the analytical signal is found by the formula T A 6 t R R, CHET -1 ET. Pr 3 T r Or Pi Pi Q where A, B are values signals of an analytic cell at, per (l of the second and second intensity values of resonance C, floor; this floor radiation; p, Jp.j, 4pinVr intensity, scattered and fluorescent radiation when introduced into the atomizing gas of reference samples at the first and second values of the intensity of the resonance radiation. AC IP 1FL r, i

Description

 The invention relates to an alshlithesky spectroscopy and can be used in the means of atomic fluorescence analysis of the composition of a substance for different areas of the national economy (ferrous and nonferrous metallurgy, geologists, mining, etc.). There is a known method for measuring atomic fluorescence, which consists in alternating translucency of the atomizer with sources of a continuous and line spectrum with subsequent extraction of a fluorescent signal. The fluorescent signal is extracted by subtracting from the signal, due to the scattered and fluorescent radiation of the source of the line spectrum, the signal of the scattered radiation from the source of the continuous spectrum. The subtraction is carried out after preliminary equalization of the scattered radiation of the sources when the idle solution (the solution that does not contain the element being analyzed and gives the scattered signal necessary for the equalization of the value to be equalized) is scored. Closest to the present invention is a method for measuring atomic fluorescence, which consists in irradiating atomic vapors of an ana lytic cell with pulsed resonance radiation followed by the release of a fluorescence signal. 2 The shortage of known methods is the low measurement accuracy, due to the fact that. the source of the line spectrum and the source of the continuous spectrum show through different parts of the flame. In addition, the lack of accuracy of measurements due to the need to increase the width of the monochromator slit in the case of a low intensity of the scattered radiation of a continuous spectrum source, as well as the inability to perform equalization, if the intensity of the radiation of a continuous spectrum source is less than the intensity of scattered radiation of a linear spectrum source (in this spectral range of wavelengths). The purpose of the invention is to improve the accuracy of atomic-fluorescent measurements. The goal is achieved by the fact that, according to the method of measuring atomic fluorescence, which involves irradiating atomic vapors of the analytical cell with pulsed resonance radiation, followed by extracting the fluorescence signal, they additionally excite the analytical cell with pulsed resonance radiation, measure the intensity of the radiation of the analytical cell at two values of the resonant excitation intensity radiation, in which the ratio of the intensity of fluorescent and scattered radiation in the measured The m signal is no more than 10 times different, the magnitude of the analytical signal is found using the formula PET A L A Et - 3, Fl PI. where A, B is the intensity of the radiation of the analytical cell at the first and second values of the intensity of resonance radiation; r,, Lp 3, til ,, are, respectively, the intensity of the scattered and fluorescent radiation when the reference samples are introduced into the atomizing gas at the first and second values of the intensity of resonant radiation. An example. Measurement of fluorescence on lithium gold 242.8 them. Fluorescence is excited by a full-cathode lamp emitting a gold spectrum. The drawing shows the dependence of the fluorescence intensity and the intensity of the scattered radiation on the amplitude of the current pulse flowing through the spectral lamp. The plots are plotted on a semi-log scale. Measurements are made with an average current through the lamp cf — Yu mA. The average current through the lamp is kept constant by increasing the duty ratio of the current pulses with a corresponding increase in the amplitude of the pulse, which varies from 60 to 480 mA. The graph shows that the growth rate of the intensity of diffuse radiation is higher than the rate of change of the intensity of the fluorescent signal. This is due to the fact that, with an increase in the intensity of resonant radiation, the contour of the emission line expands and overlaps the contour of the fluorescence line. An increase in fluorescence is determined by an increase in the intensity of the exciting radiation, and a more rapid increase in the intensity of the scattered light occurs due to an increase in the intensity of the radiation from the source and the loss of its emission line contour. The ratio of the intensity of fluorescent and scattered radiation in the measured signal at two intensity values of the exciting resonant radiation should

differ by no more than 10 times, since with a larger value of this ratio, the level of spectral noise significantly increases.

To measure the fluorescent signal with the help of the dependences shown in the drawing, two power supply modes of the spectral lamp are selected, which

where Jp signals are scattered and

fluorescent radiation in the first mode; .

ZFD, 3p „- signals measured in the second mode.

Both parts of (3) are intact at

 at

 and subtracting expression (3) from expression (2), we obtain

()

ten

The intensities of Jp are measured (scattered radiation in the first and BTdpoM selected modes when a standard that does not contain the element being analyzed (gold) is introduced into the atomizer. As a reference, a solution of spectrally pure lanthanum or calcium of the required concentration can be used.

The intensities J, f of fluorescent signals are determined in two modes with the introduction of a standard solution of gold into the atomizer. Next, a solution containing an unknown concentration of gold is injected into the atomizer, and the A and B values are measured in the selected modes.

,

FA, CZ)

, about )

15

From (4) it follows

-L9T

A.-B

G5-;

3P |

F tat -11--

1PHT -.at

Pl tfl (.

The positive effect of the method is to increase the accuracy of the analysis of the composition of a substance by a factor of 2–3, so it is possible to reduce the effect of scattered radiation and spectral interference.

The method is used in an AFL-3 analyzer.

Claims (1)

METHOD OF ATOMIC FLUORESCENCE MEASUREMENT, which consists in irradiating atomic vapors of an .hypithetical cell with pulsed resonant radiation, followed by isolating the fluorescence signal, with the help of which, in order to increase the accuracy of measurements, they additionally excite the analytical cell with a pulsed resonance from radiation, measure the radiation intensity of the analytical cell at two values of the intensity of the resonant exciting radiation, at which the ratio of the intensity of the fluorescent and scattered radiation exercises in the measured signal ^ differs no more than 10 times, the value of the analytical signal is found by the formula η et ° Czm. ' _Ί 3Τ -1ET -. '' -rt -1ET P * _ where D, B are the values of the signals of the analytical cell at, the first and second values of the intensity are resonance, et _n et_et_nogo. radiation; Jp ^ Jp, respectively, intensive ' ¹ ,. scattered and fluorescence emissions when standard samples are introduced into the atomizing gas at the first and second values of the resonance radiation intensity. SU,.,. 1057820 A