Quantitative analysis method, quantitative analysis program, and X-ray fluorescence spectrometer

Patent metadata

Field	Value
Publication number	US-11782000-B2
Application number	US-202017793913-A
Country	US
Kind code	B2
Filing date	Dec 4, 2020
Priority date	Feb 12, 2020
Publication date	Oct 10, 2023
Grant date	Oct 10, 2023

Abstract

Provided are a quantitative analysis method, a quantitative analysis program, and an X-ray fluorescence. The quantitative analysis method includes: a step of acquiring a representative composition set to represent contents of analysis components; a step of acquiring a plurality of comparative compositions, in each of which the content of one of the analysis components of the representative composition is changed by a predetermined content; a detection intensity calculation step of calculating a detection intensity indicating an intensity of fluorescent X-rays detected under the influence of the geometry effect through use of an FP method with respect to a virtual sample having a thickness set in advance and being indicated by each of the representative composition and the comparative compositions; and a step of calculating a matrix correction coefficient for each of the analysis components based on the detection intensity.

First claim

The invention claimed is:

1. A quantitative analysis method, comprising:
a representative composition acquisition step of acquiring a representative composition, which is a composition expressed by contents of analysis components contained in an unknown sample to be analyzed, and is set to represent the contents of the analysis components;
a comparative composition acquisition step of acquiring a plurality of comparative compositions, in each of which the content of one of the analysis components contained in the representative composition is changed by a predetermined content;
a detection intensity calculation step of, assuming that a virtual sample having a thickness set in advance and being indicated by each of the representative composition and the comparative compositions has been irradiated with primary X-rays, calculating a detection intensity indicating an intensity of fluorescent X-rays detected under an influence of a geometry effect through use of a fundamental parameter method; and
a matrix correction coefficient calculation step of calculating a matrix correction coefficient α j for each of the analysis components through use of a calibration curve equation expressed by:
W i =( bI i +c )(1+Σα j W j )  [Math. 1]

W i =( aI j 2 +bI i +c )(1+Σα j W i ); or  [Math. 2]

W i =bI i (1+Σα j W i )+ c , where:  [Math. 3]

W i represents a mass fraction of one component “i” included in the analysis components;
“a”, “b”, and “c” each represent a constant;
I i represents the detection intensity calculated for the component “i” in the detection intensity calculation step;
α j represents the matrix correction coefficient for the component “i” with respect to a coexisting component “j”; and
W j represents a mass fraction of the coexisting component “j”,
wherein the thickness set in advance as the thickness of the virtual sample, and a thickness of the unknown sample, are the same.

2. The quantitative analysis method according to claim 1 , wherein the detection intensity calculation step includes:
a division step of dividing a thickness of the virtual sample from the front surface of the virtual sample to a predetermined position with fixed intervals; and
a total sum calculation step of calculating a total sum of the detection intensity calculated for each of the divisions.

3. The quantitative analysis method according to claim 2 , wherein the predetermined position is set to:
a position at which the detection intensity becomes 0 when a thickness of the unknown sample is larger than a thickness from the front surface to the position at which the detection intensity becomes 0; and
a position of a back surface of the unknown sample when the thickness of the unknown sample is smaller than the thickness from the front surface to the position at which the detection intensity becomes 0.

4. The quantitative analysis method according to claim 1 , wherein the detection intensity calculation step includes:
an emission intensity calculation step of, assuming that the virtual sample indicated by each of the representative composition and the comparative compositions has been irradiated with primary X-rays, calculating an emission intensity indicating the intensity of the fluorescent X-rays emitted from each of the analysis components, as a function of a position from the front surface of the virtual sample with the geometry effect being ignored;
a detection ratio acquisition step of acquiring, assuming that a virtual sample indicated by a given composition has been irradiated with primary X-rays, a detection ratio as the function of the position from the front surface, the detection ratio representing a ratio between an emission intensity indicating the intensity of the fluorescent X-rays emitted from the virtual sample and the detection intensity of the fluorescent X-rays detected under the influence of the geometry effect for the lines of emitted fluorescent X-rays; and
a multiplication step of multiplying the emission intensity by the detection ratio to calculate the detection intensity as the function of the position from the front surface.

5. The quantitative analysis method according to claim 1 , further comprising:
a standard sample measuring step of irradiating a plurality of standard samples containing the analysis components and having known contents with primary X-rays, and measuring the intensity of the fluorescent X-rays emitted from each of the analysis components;
a calibration curve creation step of creating a calibration curve expressed by the calibration curve equation for each of the analysis components, based on the intensity of the fluorescent X-rays measured in the standard sample measuring step and the matrix correction coefficient;
an unknown sample measuring step of irradiating the unknown sample with primary X-rays, and measuring the intensity of the fluorescent X-rays for each of the analysis components; and
a content calculation step of calculating the content of each of the analysis components contained in the unknown sample, based on the intensity of the fluorescent X-rays measured in the unknown sample measuring step and the calibration curve,
wherein all the thicknesses of the plurality of standard samples are the same as the thickness set in advance as the thickness of the virtual sample and the thickness of the unknown sample.

6. The quantitative analysis method according to claim 1 ,
wherein the detection intensity calculation step is a step of calculating the detection intensity through use of a Monte Carlo simulation, and
wherein the detection intensity calculation step includes the steps of:
setting, as parameters, a thickness of the virtual sample, the intensity of the primary X-rays to be applied to each position on the front surface of the virtual sample, and an incident angle with respect to the front surface of the primary X-rays;
determining, based on randomly determined values, a generation position of the primary X-rays on an X-ray tube target, a direction in which the primary X-rays are emitted, and energy of the primary X-rays; and
calculating the intensity of the fluorescent X-rays for a predetermined position using the detection intensity for each trajectory from the generation position of the primary X-rays to the front surface.

7. A non-transitory computer-readable information storage medium for storing a program for causing a computer used for an X-ray fluorescence spectrometer to execute:
a representative composition acquisition step of acquiring a representative composition, which is a composition expressed by contents of analysis components contained in an unknown sample to be analyzed, and which is set to represent the contents of the analysis components;
a comparative composition acquisition step of acquiring a plurality of comparative compositions, in each of which the content of one of the analysis components contained in the representative composition is changed by a predetermined content;
a detection intensity calculation step of, assuming that a virtual sample having a thickness set in advance and being indicated by each of the representative composition and the comparative compositions has been irradiated with primary X-rays, calculating a detection intensity indicating an intensity of fluorescent X-rays detected under the influence of a geometry effect through use of a fundamental parameter method; and
a matrix correction coefficient calculation step of calculating a matrix correction coefficient α j for each of the analysis components through use of a calibration curve equation expressed by:
W i =( bI i +c )(1+Σα j W j );  [Math. 1]

W i =( aI i 2 +bI i +c )(1+Σα i W j ); or

W i =bI i (1

Assignees

• Rigaku Denki Co Ltd

Inventors

• Kataoka Yoshiyuki
• Kusakabe Yasushi

Classifications

• G01N23/223 Primary

  by irradiating the sample with X-rays or gamma-rays and by measuring X-ray fluorescence · CPC title

• G01N23/2208

  all measurements being of a secondary emission, e.g. combination of SE measurement and characteristic X-ray measurement · CPC title

• G01N2223/076

  X-ray fluorescence · CPC title

• G01N2223/1016

  X-ray · CPC title

• G01N2223/304

  electric circuits, signal processing · CPC title