JP2014041065A - X-ray analyzer and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an X-ray analyzer capable of further accurate quantitative analysis, and a computer program.SOLUTION: The X-ray analyzer calculates first intensities of peaks of each element by peak resolution of a spectrum of characteristic X-rays based on the assumption of an intensity ratio of a plurality of peaks due to the element, and variation of peak intensities is limited and then peak resolution in a limited energy range is performed, and concentrations of a plurality of elements are calculated on the basis of obtained second intensities of peaks. The X-ray analyzer calculates an intensity ratio of a plurality of peaks due to each element on the basis of calculated concentrations of the plurality of elements and calculates third intensities of peaks of each element by peak resolution using the calculated intensity ratio. Processing is repeated until variation of peak intensities is sufficiently reduced, whereby concentrations of a plurality of elements included in a sample S are calculated more accurately than prior arts.

Description

  The present invention relates to an X-ray analyzer and a computer program for performing qualitative and quantitative calculation of a sample composition by analyzing a spectrum of X-rays generated from a sample.

  Conventionally, X-ray analysis is used to examine the composition of a substance. X-ray analysis is an analysis technique in which a sample is irradiated with radiation such as X-rays or electron beams, and a qualitative analysis or quantitative analysis of elements contained in the sample is performed from a spectrum of characteristic X-rays generated from the sample. In particular, when the radiation for irradiation is X-rays, the characteristic X-rays are called fluorescent X-rays. In order to perform quantitative analysis of an element from the spectrum of characteristic X-rays, first, a theoretical spectrum obtained by superposing peaks attributed to a plurality of elements is compared with a measured spectrum, and a signal attributed to each element is compared. Perform peak separation to determine the intensity ratio. Based on the intensity of the peak obtained by the peak separation, the concentration of each element is calculated. There are a plurality of methods for calculating the concentration. For example, the FP (fundamental parameter) method is used.

  The intensity of characteristic X-rays measured due to one element is influenced by other elements in the sample due to causes such as absorption of characteristic X-rays by other elements. Since the degree of influence varies depending on the energy of characteristic X-rays, the intensity ratio of a plurality of characteristic X-rays having different energy due to one element is also affected by other elements in the sample and changes. For example, although the intensity ratio of a plurality of characteristic X-rays such as Kα1, Kα2, and Kβ from a certain element is inherently unique to the element, the measured intensity ratio varies depending on the sample composition. In the FP method, the concentration of each element in a sample is calculated in consideration of such a change in signal intensity due to the sample composition. In Patent Document 1, in order to perform a more accurate analysis, the signal intensity ratio obtained from the concentration is compared with the signal intensity ratio obtained by peak separation, and the signal intensity ratio is not converged. In addition, a technique is disclosed in which peak separation is performed again using the intensity ratio of the signal obtained from the concentration. In Non-Patent Document 1, after performing peak separation once, it is limited to a specific peak having a high intensity, and by performing detailed peak separation while changing the peak intensity, the intensity of the specific peak is accurately determined. And a technique for calculating the concentration of each element is disclosed.

JP 2012-68084 A

Akimichi Kira, “Desktop X-ray fluorescence elemental analyzer (MESA-500)”, Readout, HORIBA, Ltd., July 1993, No. 7, p. 95-103

  In the X-ray analysis described in Patent Document 1, depending on the composition or structure of the sample, peak separation is difficult and accurate quantitative analysis is difficult, or convergence is slow and analysis may take a long time. For example, when the concentration of a harmful substance in a sample is obtained using the method described in Non-Patent Document 1, it is difficult to separate the peaks of the arsenic signal and the lead signal, and accurate quantitative analysis is difficult. FIG. 8 is a schematic characteristic diagram showing an example of a fluorescent X-ray spectrum caused by arsenic and lead. In the figure, the horizontal axis indicates energy, and the vertical axis indicates signal intensity. In FIG. 8, the Kα and Kβ peaks of arsenic (As) are indicated by solid lines, and the Lα and Lβ peaks of lead (Pb) are indicated by broken lines. The arsenic Kα peak used for concentration calculation and the lead Lα peak almost overlap each other. When a detailed peak separation limited to the arsenic Kα peak and the lead Lα peak is performed, the spectrum obtained by superimposing both peaks hardly changes even if the ratio of arsenic and lead is changed. It is difficult to accurately determine the intensity of each peak. For this reason, it is difficult to obtain accurate concentrations of arsenic and lead.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an X-ray analysis apparatus and a computer program that enable more accurate quantitative analysis.

  An X-ray analyzer according to the present invention is an X-ray analyzer that obtains concentrations of a plurality of elements contained in a sample based on a characteristic X-ray spectrum generated from the sample. An intensity ratio specifying unit that sets the intensity ratio to a predetermined value, and a first intensity that calculates the first intensity of the peak of each element included in the spectrum of the characteristic X-ray by performing peak separation using the intensity ratio The second intensity of the peak of each element is calculated by performing peak separation for a specific energy range of the spectrum after limiting the change from the first intensity of the peak intensity and the calculation unit to a predetermined range. A second intensity calculator that calculates the concentration of a plurality of elements contained in the sample based on the second intensity of the peak of each element, and a concentration of the plurality of elements calculated by the concentration calculator On the basis of the, An intensity ratio respecifying unit that calculates the intensity or intensity ratio of a plurality of peaks caused by an element, and the spectrum is obtained by performing peak separation using the intensity or the intensity ratio calculated by the intensity ratio respecifying unit. A third intensity calculator for calculating a third intensity of the peak of each element included in the element, a difference between the second intensity and the third intensity, or a quantitative value of a specific type of amount obtained from the second intensity and the third intensity. A determination unit that determines whether or not the difference is within a predetermined range, and a plurality of elements included in the sample when the difference between the second intensity and the third intensity, or the difference between the quantitative values is within the predetermined range A density determining unit that determines the density of the density to the density calculated by the density calculating unit.

  In the X-ray analysis apparatus according to the present invention, the second intensity calculation unit limits the change in the peak intensity so that the scaling factor compared to the first intensity of the peak intensity falls within a non-negative predetermined range. Features.

  The X-ray analyzer according to the present invention uses the first intensity calculated by the third intensity calculator when the difference between the second intensity and the third intensity, or the difference between the quantitative values is outside a predetermined range. As the intensity, the apparatus further includes a first intensity specifying unit that returns the calculation to the second intensity calculating unit.

  The X-ray analyzer according to the present invention uses the second intensity calculated by the third intensity calculator when the difference between the second intensity and the third intensity or the difference between the quantitative values is outside a predetermined range. As the intensity, the apparatus further includes a second intensity specifying unit that returns the calculation to the concentration calculation unit.

  The X-ray analyzer according to the present invention returns the calculation to either the second intensity calculation unit or the concentration calculation unit when the difference between the second intensity and the third intensity or the difference between the quantitative values is outside a predetermined range. And a setting unit that sets whether or not the setting unit returns the calculation to the second intensity calculating unit, and the difference between the second intensity and the third intensity, or the difference between the quantitative values is out of a predetermined range. The first intensity specifying unit for returning the calculation to the second intensity calculating unit, with the third intensity calculated by the third intensity calculating unit as the first intensity, and the setting unit calculating to the concentration calculating unit When the difference between the second intensity and the third intensity, or the difference between the quantitative values is outside a predetermined range, the third intensity calculated by the third intensity calculator is set as the second intensity. And a second intensity specifying unit that returns the calculation to the concentration calculating unit.

  An X-ray analyzer according to the present invention includes an irradiation unit that irradiates a sample with radiation, an X-ray detection unit that detects characteristic X-rays generated from the sample, and a spectrum of characteristic X-rays detected by the X-ray detection unit. And a spectrum generation unit for generating the spectrum generation unit.

  A computer program according to the present invention is a computer program that causes a computer to execute a process for determining the concentration of a plurality of elements contained in a sample based on a characteristic X-ray spectrum generated from the sample. A step of determining the intensity ratio of the plurality of peaks to a predetermined value, and a step of calculating the first intensity of the peak of each element included in the spectrum of the characteristic X-ray by performing peak separation using the intensity ratio And calculating the second intensity of the peak of each element by limiting the change of the peak intensity from the first intensity within a predetermined range and performing peak separation for a specific energy range of the spectrum. A concentration calculating step for calculating concentrations of a plurality of elements contained in the sample based on a second intensity calculating step and a second intensity of the peak of each element; Calculating the intensity ratio of a plurality of peaks attributed to each element based on the calculated concentration of the plurality of elements, and performing peak separation using the calculated intensity ratio, thereby obtaining the spectrum. The step of calculating the third intensity of the peak of each element included in the element, the difference between the second intensity and the third intensity, or the difference in the quantitative value of the amount of a specific type obtained from the second intensity and the third intensity is within a predetermined range. The step of determining whether or not the difference between the second intensity and the third intensity, or the difference between the quantitative values is within a predetermined range, the concentration of a plurality of elements contained in the sample, And a step of determining a density calculated in the density calculating step.

  The computer program according to the present invention allows the computer to calculate the second intensity using the third intensity as the first intensity when the difference between the second intensity and the third intensity or the difference between the quantitative values is outside a predetermined range. The process further includes a step of returning the process to the step.

  When the difference between the second intensity and the third intensity or the difference between the quantitative values is outside the predetermined range, the computer program according to the present invention sets the third intensity as the second intensity and proceeds to the concentration calculation step. The process further includes a step of returning the process.

  In the present invention, after calculating the first intensity of the peak due to each element by peak separation, the X-ray analyzer performs detailed peak separation in a narrow energy range after limiting the change in peak intensity, Based on the second intensity of the obtained peak, the concentration of each element is calculated. In particular, the scaling factor compared to the first intensity of the peak intensity is limited to a non-negative predetermined range. Further, the X-ray analyzer calculates the intensity ratio of a plurality of peaks caused by each element from the calculated concentrations of the plurality of elements. This intensity ratio is affected by the concentration of the coexisting elements. Further, the X-ray analyzer calculates the third intensity of the peak by peak separation using the calculated intensity ratio, and is obtained from the difference between the second intensity and the third intensity, or the second intensity and the third intensity. The accuracy of the concentration is determined by comparing the difference in the amount such as the concentration.

  Further, in the present invention, the X-ray analyzer is a detailed apparatus in a narrow energy range when the difference between the second intensity and the third intensity or the difference between the amounts obtained from the second intensity and the third intensity is large. Return processing to peak separation. The X-ray analyzer repeats the process until the difference between the second intensity and the third intensity, or the difference between the amounts obtained from the second intensity and the third intensity becomes small, and the accurate concentration of each element is calculated. .

  Further, in the present invention, the X-ray analyzer is a detailed apparatus in a narrow energy range when the difference between the second intensity and the third intensity or the difference between the amounts obtained from the second intensity and the third intensity is large. The peak separation is omitted, and the concentration of each element is calculated using the third intensity of the peak as the second intensity. Detailed peak separation processing is omitted in the second and subsequent processing when the processing is repeated, and the processing time is shortened.

  In the present invention, the X-ray analyzer can set whether to repeat the process including detailed peak separation in a narrow energy range, or to omit the detailed peak separation after the second time and repeat the process. It is possible to change. As a result, appropriate processing according to the analysis target is possible.

  In the present invention, the X-ray analyzer exhibits excellent effects such as performing accurate peak separation and performing quantitative analysis of elements contained in a sample with higher accuracy than before.

It is a block diagram which shows the structure of the X-ray analyzer which concerns on this Embodiment. It is a block diagram which shows the internal structure of information processing apparatus. It is a block diagram which shows the function structure of CPU. It is a flowchart which shows the procedure of the process of the X-ray analysis which an X-ray analyzer performs. It is a flowchart which shows the procedure of the process of the X-ray analysis which an X-ray analyzer performs. It is a typical characteristic view for explaining the intensity ratio of a plurality of peaks. It is a typical characteristic figure showing an example of peak separation. It is a typical characteristic figure showing an example of a spectrum of fluorescence X-rays resulting from arsenic and lead.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
FIG. 1 is a block diagram showing the configuration of the X-ray analyzer according to the present embodiment. The X-ray analyzer includes an X-ray source 11 that irradiates a sample S with X-rays, a sample stage 13 on which the sample S is placed, and an X-ray detector 12 that detects X-rays. In FIG. 1, the cross section of the sample stage 13 and the sample S is shown. The X-ray source 11, the sample stage 13, and the X-ray detector 12 are disposed in a housing (not shown) for blocking X-rays. The X-ray source 11 is, for example, an X-ray tube and corresponds to the irradiation unit in the present invention. The X-ray detection unit 12 is configured using an X-ray detection element such as a Si element. The X-ray source 11 irradiates the sample S with X-rays, the sample S generates fluorescent X-rays, and the X-ray detector 12 detects the fluorescent X-rays generated from the sample S. In FIG. 1, X-rays irradiated from the X-ray source 11 to the sample S and fluorescent X-rays generated by the sample S and detected by the X-ray detection unit 12 are indicated by arrows. The X-ray detection unit 12 outputs a signal proportional to the detected energy of the fluorescent X-ray.

  The X-ray detection unit 12 is connected to a spectrum generation unit 21 that processes the output signal. The spectrum generation unit 21 receives the signal output from the X-ray detection unit 12, counts the signal of each value, and the relationship between the fluorescent X-ray energy detected by the X-ray detector 12 and the count number, that is, the fluorescent X-ray. The process which produces | generates the spectrum of is performed. In addition, the X-ray analysis apparatus includes a control unit 22 that controls operations of the X-ray source 11 and the spectrum generation unit 21. The control unit 22 is connected to the X-ray source 11 and the spectrum generation unit 21. Furthermore, the X-ray analysis apparatus includes an information processing apparatus 3 that executes a process for obtaining the concentration of an element contained in the sample S from the fluorescent X-ray spectrum. The information processing device 3 is connected to the spectrum generation unit 21 and the control unit 22.

  FIG. 2 is a block diagram illustrating an internal configuration of the information processing apparatus 3. The information processing apparatus 3 is configured using a computer such as a personal computer. The information processing apparatus 3 reads information from a CPU (Central Processing Unit) 31 that performs calculations, a RAM (Random Access Memory) 32 that stores temporary data generated along with the calculations, and a recording medium 4 such as an optical disk. A drive unit 33 and a non-volatile storage unit 34 such as a hard disk are provided. The information processing apparatus 3 includes an operation unit 35 such as a keyboard or a mouse that accepts a user operation, a display unit 36 such as a liquid crystal display, and an interface unit 37. The interface unit 37 is connected to the X-ray source 11 and the spectrum generation unit 21. The CPU 31 causes the drive unit 33 to read the computer program 41 recorded on the recording medium 4 and stores the read computer program 41 in the storage unit 34. The computer program 41 is loaded from the storage unit 34 to the RAM 32 as necessary, and the CPU 31 executes processing necessary for the X-ray analyzer according to the loaded computer program 41. The computer program 41 may be downloaded from outside the information processing apparatus 3.

  The storage unit 34 stores element data indicating the characteristics of fluorescent X-rays caused by specific elements. The element data includes information indicating energy of a plurality of peaks included in the spectrum of the fluorescent X-ray due to a specific element. The element data includes information indicating the initial value of the intensity ratio of a plurality of peaks caused by a specific element. The initial value of the intensity ratio is an intensity ratio of a plurality of peaks obtained under ideal conditions where the intensity of fluorescent X-rays caused by a specific element does not change. Here, the intensity ratio is the ratio of the intensity of another peak when the intensity of a specific peak is used as a reference among a plurality of peaks attributed to the same element. The reference may be changed between the K-line peak and the L-line peak. For example, the ratio of the intensity of one peak included in a plurality of peaks of the K line is determined based on the intensity ratio of the peak of another K line based on the intensity of one peak included in the plurality of peaks of the K line. The intensity ratio of other L-line peaks is defined. Element data is stored for each of a plurality of elements. In addition, the storage unit 34 stores environment data indicating a measurement environment that affects the detection intensity of fluorescent X-rays. The environmental data includes, for example, an applied voltage to the X-ray source 11 that is an X-ray tube, an irradiation angle of the X-ray from the X-ray source 11 to the sample S, a distance from the sample stage 13 to the X-ray detector 12, Information such as the angle of X-rays incident on the X-ray detection unit 12 from the sample S, the type of atmosphere, and the detection efficiency of the X-ray detection unit 12 is included.

  FIG. 3 is a block diagram showing a functional configuration of the CPU 31. CPU31 contains the setting part 301 which sets the flow of a process as a function part. The CPU 31 includes an intensity ratio specifying unit 302 that specifies an intensity ratio of a plurality of peaks caused by each element included in the sample S, and processing is passed from the setting unit 301 to the intensity ratio specifying unit 302. The CPU 31 includes a first intensity calculation unit 303 that calculates the first intensity of the peak of each element by peak separation using the intensity ratio specified by the intensity ratio specifying unit 302. The CPU 31 includes a second intensity calculator 304 that calculates the second intensity of each element peak by more detailed peak separation based on the first intensity calculated by the first intensity calculator 303. The CPU 31 includes a concentration calculator 305 that calculates the concentration of each element from the second intensity calculated by the second intensity calculator 304. The CPU 31 includes an intensity ratio re-specification unit 306 that calculates an intensity ratio of a plurality of peaks caused by each element from the concentrations of the plurality of elements calculated by the concentration calculation unit 305. The CPU 31 includes a third intensity calculator 307 that calculates a third intensity of each element peak by peak separation using the intensity ratio calculated by the intensity ratio re-identifier 306. The CPU 31 includes a determination unit 308 that determines whether the difference between the second intensity calculated by the second intensity calculation unit 304 and the third intensity calculated by the third intensity calculation unit 307 is within a predetermined range. The CPU 31 includes a density determination unit 309 that determines the density when the determination unit 308 determines that the difference between the second intensity and the third intensity is within a predetermined range. The CPU 31 determines that the difference between the second intensity and the third intensity is outside the predetermined range by the determination unit 308, and if the setting unit 301 is set to return the process to the density calculation unit 305, the CPU 31 A second intensity specifying unit 310 that returns the processing to the concentration calculation unit 305 with the intensity as the second intensity is included. Further, when the determination unit 308 determines that the difference between the second intensity and the third intensity is outside the predetermined range, the CPU 31 is set to return the processing to the second intensity calculation unit 304 by the setting unit 301. In addition, a first intensity specifying unit 311 is provided that sets the third intensity as the first intensity and returns the processing to the second intensity calculating unit 304. Each functional unit shown in FIG. 3 is realized by the CPU 31 executing information processing according to the computer program 41.

  4 and 5 are flowcharts showing the procedure of the X-ray analysis process executed by the X-ray analyzer. The CPU 31 of the information processing device 3 executes the following processing according to the computer program 41. The user places the sample S on the sample stage 13, operates the operation unit 35, and inputs an instruction for starting X-ray analysis. The CPU 31 displays a menu for accepting information necessary for X-ray analysis on the display unit 36, and accepts necessary information when the user operates the operation unit 35 (S1). For example, a menu for selecting the type of sample is displayed, the type of sample is selected by the user's operation, and the CPU 31 accepts designation of the type of sample. Further, for example, a menu for selecting an element whose concentration is to be calculated is displayed, the element is selected by a user operation, and the CPU 31 accepts designation of the element whose concentration is to be calculated. In addition, a menu for selecting whether to return the process to step S8 or step S9 in step S15, which will be described later, is displayed and selected by the user's operation. Note that the CPU 31 may perform a process of determining a step to which the process is to be returned in accordance with the selection of an element whose sample type or concentration is to be calculated. In addition, the CPU 31 may perform processing for receiving measurement conditions such as energy of X-rays irradiated by the X-ray source 11.

  CPU31 memorize | stores the received information in RAM32 or the memory | storage part 34, and sets the destination step which returns a process in the case of step S15 (S2). Next, the CPU 31 outputs an X-ray irradiation instruction from the interface unit 37 to the control unit 22, and the control unit 22 causes the X-ray source 11 to irradiate the sample S (S3). X-ray fluorescence is generated from the sample S irradiated with X-rays, and the X-ray detection unit 12 detects the fluorescent X-rays and outputs a signal corresponding to the detected fluorescent X-rays to the spectrum generation unit 21. The generation unit 21 generates a fluorescent X-ray spectrum (S4). The spectrum generation unit 21 outputs the generated fluorescent X-ray spectrum to the information processing device 3. The spectrum of the fluorescent X-ray is input to the interface unit 37, and the CPU 31 stores the spectrum data in the RAM 32 or the storage unit 34. Next, the CPU 31 performs a process of designating a plurality of elements whose concentrations should be calculated based on the fluorescent X-ray spectrum (S5). In step S5, for example, the CPU 31 performs processing for designating the element selected in step S1. For example, CPU31 may detect the some peak contained in a spectrum, and may perform the process which designates the element which emits a fluorescent X-ray with energy close to each peak. Further, the CPU 31 may perform a process of designating all elements that can calculate the concentration. Further, the CPU 31 may perform a process of accepting designation of an element whose concentration is to be calculated at this stage from the user.

  Next, the CPU 31 specifies the intensity ratio by setting the intensity ratio of the plurality of peaks caused by the designated element to the initial value recorded in the element data (S6). FIG. 6 is a schematic characteristic diagram for explaining the intensity ratio of a plurality of peaks. In the figure, the horizontal axis indicates energy, and the vertical axis indicates signal intensity. FIG. 6 schematically shows a fluorescent X-ray spectrum caused by one element. From one element, a plurality of peaks such as Lα1, Lα2, and Lβ1 are obtained. In a state where there is no effect of changing the peak intensity due to the coexistence of other elements, the intensity ratio of the plurality of peaks is a unique value, and this unique value is recorded as the initial value in the element data. In step S6, the intensity ratio is temporarily set to an initial value.

  Next, the CPU 31 calculates the first intensity of the peak due to each of the plurality of elements whose concentration is to be calculated by performing peak separation on the spectrum of the fluorescent X-ray (S7). FIG. 7 is a schematic characteristic diagram showing an example of peak separation. In the figure, the horizontal axis indicates energy, and the vertical axis indicates signal intensity. In FIG. 7, the spectrum of the measured fluorescent X-ray is shown by a solid line. CPU31 produces | generates the theoretical spectrum which consists of a some peak resulting from a specific element using the specified intensity | strength ratio. Similarly, the CPU 31 generates a theoretical spectrum for each of a plurality of elements whose concentrations are to be calculated. In FIG. 7, a theoretical spectrum for one element A is indicated by a broken line, and a theoretical spectrum for another element B is indicated by a one-dot chain line. The CPU 31 adds a plurality of theoretical spectra corresponding to a plurality of elements, generates a synthetic spectrum with the background added, and compares the generated synthetic spectrum with the measured fluorescent X-ray spectrum. Note that the CPU 31 may compare a combined spectrum obtained by adding a plurality of theoretical spectra with a spectrum obtained by subtracting the background from the measured fluorescent X-ray spectrum. The CPU 31 calculates the intensity of the peak due to each element by the least square method so that the synthesized spectrum becomes the best approximation of the measured spectrum of the fluorescent X-ray. The calculated peak intensity is defined as the first intensity. In step S6, the CPU 31 performs processing for specifying a part of the peak intensity by setting the peak intensity due to a part of the elements to an initial value, and uses the specified peak intensity in step S7. Peak separation may be performed. The initial value of the peak intensity is a value that is theoretically obtained, for example.

  Next, the CPU 31 calculates the second intensity of the peak due to each element by performing peak separation on the spectrum in which the energy range is limited after limiting the change in the intensity of the peak due to each element. (S8). In the peak separation in step S8, the scaling factor compared to the first intensity of the peak intensity due to each element is limited to a non-negative predetermined range. For example, the magnification is zero to two times. That is, the peak intensity of each element that can be taken in the calculation of peak separation is not less than zero and not more than twice the first intensity.

  FIG. 7 shows the spectrum energy range used in the peak separation in step S8. The energy range used for peak separation is a partial energy range included in the measured spectrum of fluorescent X-rays. The energy range used in the peak separation in step S8 is a range in which a peak mainly used for calculating the concentration among a plurality of peaks attributed to each element is included, and usually the peak intensity is higher than other ranges. Is a range in which becomes higher. In addition, this energy range is desirably a range in which the background intensity is low. The energy range used for the peak separation in step S8 is determined in advance by the computer program 41.

  Note that the CPU 31 may determine the energy range according to the information received in step S1. For example, the CPU 31 displays a menu for selecting an energy range on the display unit 36 in step S1, and accepts the selection of the energy range. In addition, for example, information indicating an appropriate energy range corresponding to the combination of elements whose sample type or concentration is to be calculated is stored in the storage unit 34, and the CPU 31 performs steps according to the sample type or the combination of elements. You may perform the process which determines the energy range utilized by the peak separation of S8. Further, the CPU 31 may define an energy range for each element. For example, the CPU 31 may accept selection of the energy range for each element in step S <b> 1, and may determine the energy range for each element based on information stored in advance in the storage unit 34. In this case, peak separation is performed in each of the energy ranges determined for each element. In this case, the energy range used for peak separation may include a plurality of discontinuous energy ranges.

  In step S8, the CPU 31 adds a plurality of peaks included in the energy range restricted among the peaks caused by the plurality of elements, and further generates a synthesized spectrum by adding the background. Compare the portion of the measured spectrum that falls within the limited energy range. The CPU 31 limits the change in the intensity of each peak so that the scaling factor compared to the first intensity falls within a non-negative predetermined range, while making the best approximation of the spectrum of the measured fluorescent X-ray spectrum. Thus, the intensity of the peak due to each element is calculated by the least square method.

In order to limit the change in peak intensity, for example, the intensity of each peak is represented by a function including an arc tangent of an arbitrary variable, and the scaling factor compared to the first intensity of the peak intensity is within a predetermined range according to the change in the variable. To change. The scaling factor compared to the first intensity of the peak intensity is K, and x is a variable −∞ <x <∞, and K = 1 + (2 / π) · arctan (x). K changes in the range of 0-2 according to the change of x. Assuming that the spectrum where two peaks overlap is f, the first intensity of one peak is I ₀ , the scaling factor is K ₀ , the first intensity of the other peak is I ₁ , and the scaling factor is K ₁ , f = K ₀ I ₀ + K ₁ I ₁ . By calculating f in a range of −∞ <x <∞ and performing the least square method, peak separation can be performed in which the scaling factor compared to the first intensity of the peak intensity is limited to zero to twice. If C is a positive value and expressed as K = C / 2 + (C / π) · arctan (x), the scaling factor can be limited to a range of zero to C times. Further, the minimum value of the scaling factor may be a value larger than zero. Other methods may be used as a method of limiting the scaling factor. If the energy range used in step S8 includes a plurality of peaks due to one element, the intensity of each peak is calculated individually. The peak intensity calculated in step S8 is set as the second intensity.

  In addition, CPU31 may perform the process which determines the range of the magnification rate of peak intensity according to an element. The scaling factor for each element may be determined in advance. The CPU 31 may accept the range of the scaling factor for each element in step S1. In step S8, the CPU 31 may display the fluorescent X-ray spectrum on the display unit 36, and perform a process of accepting the element-specific magnification range by operating the operation unit 35.

  Next, the CPU 31 calculates the concentration of each element contained in the sample S based on the calculated second intensity of the peak of each element (S9). In step S9, the CPU 31 calculates the density by, for example, the FP method. The CPU 31 converts the second intensity of the peak of each element into the intensity on the surface of the sample S based on the measurement environment recorded in the environmental data, and the initial value of the concentration from the converted second intensity of the peak of each element. Calculate Further, the CPU 31 calculates the theoretical intensity of the peak of each element based on the calculated concentrations of the plurality of elements. At this time, the CPU 31 calculates the theoretical intensity of the peak including the influence of the coexisting element in which the peak intensity of each element changes according to the concentration of the other element. The CPU 31 recalculates the concentration of each element by comparing the calculated theoretical peak intensity of each element with the second intensity. The CPU 31 determines whether or not the difference in concentration is within a predetermined range. If the difference in concentration is outside the predetermined range, the process returns to the calculation of the theoretical intensity of the peak of each element, and the difference in concentration. Is within the predetermined range, the concentration calculation is terminated. The peak used for the calculation is a peak included in the energy range used in the peak separation in step S8. Note that the CPU 31 may calculate the concentration using a method other than the FP method.

  Next, the CPU 31 calculates a plurality of peak intensities of each element based on the calculated concentration of each element, and calculates an intensity ratio of the plurality of peaks attributed to each element (S10). In step S10, the CPU 31 changes each of the plurality of peak intensities of each element according to the concentration of the coexisting element so as to reflect the influence of the coexisting element in which the peak intensity of one element changes according to the concentration of the other element. And calculating the intensity ratio of a plurality of peaks of each element. For example, when calculating the peak intensity of one element using the FP method, the CPU 31 also calculates the absorption effect and secondary excitation effect of the other element, and individually calculates a plurality of peak intensities of each element. To calculate. The CPU 31 calculates the intensity ratio over an energy range wider than the energy range used in the peak separation in step S8. By this processing, the intensity ratio of the plurality of peaks attributed to each element is specified again. Next, the CPU 31 calculates the third intensity of the peak due to each element by performing peak separation on the measured spectrum of the fluorescent X-ray using the intensity ratio calculated in step S10 (S11). ). The calculation method in step S11 is the same as that in step S7, but the intensity ratio value is changed. Note that the CPU 31 only calculates a plurality of peak intensities of each element in step S10, and may perform peak separation using the plurality of peak intensities of each element in step S11. Even in this process, the intensity ratio of a plurality of peaks substantially due to each element is specified again.

  Next, the CPU 31 determines whether or not the difference between the second intensity and the third intensity of the plurality of element peaks is within a predetermined range (S12). In step S12, for example, it is determined whether or not the absolute value of the difference between the second intensity and the third intensity is 1% or less of the second intensity. Further, for example, it is determined whether or not the ratio between the second intensity and the third intensity is within a range of 0.99 to 1.01. In step S12, the second intensity converted to the intensity on the surface of the sample S may be compared with the third intensity.

  When the difference between the second intensity and the third intensity is within the predetermined range in step S12 (S12: YES), the CPU 31 determines the concentration of the plurality of elements contained in the sample S as the calculation result of step S9 ( S13). Next, the CPU 31 stores the determined concentration of each element in the storage unit 34 and displays it on the display unit 36 (S14), and ends the process. Note that the CPU 31 may perform a process of outputting the concentration of each element to a printer (not shown).

  If the difference between the second intensity and the third intensity is outside the predetermined range in step S12 (S12: NO), the CPU 31 determines whether or not the process is set to return to step S8 (S15). When the setting is made to return the process to step S8 (S15: YES), the CPU 31 sets the calculated third intensity as the first intensity (S16), and returns the process to step S8. When the setting is made to return the process to step S9 (S15: NO), the CPU 31 sets the calculated third intensity as the second intensity (S17), and returns the process to step S9. The process performed by returning the process to step S8 is a process of repeating the peak separation and the concentration calculation while calculating the intensity ratio of a plurality of peaks caused by each element according to the concentration. Further, the process performed by returning the process to step S9 is a process in which the peak separation process in which the change in the peak intensity in step S8 is limited is omitted for the second and subsequent steps and the peak separation and the concentration calculation are repeated.

  In step S12, the CPU 31 calculates a quantitative value of a specific type from the second intensity and the third intensity, and the difference between the quantitative value obtained from the second intensity and the quantitative value obtained from the third intensity is predetermined. You may perform the process which determines whether it is in the range. For example, the CPU 31 calculates the concentration of a specific element from the second intensity and the third intensity, and determines whether or not the difference between the concentration calculated from the second intensity and the concentration calculated from the third intensity is within a predetermined range. You may perform the process to determine. Further, for example, the CPU 31 may calculate the intensity ratio of the second intensity and the intensity ratio of the third intensity due to a specific element, and compare the calculated intensity ratio. Further, for example, when the sample S includes one or more films, the CPU 31 calculates the film thickness of the specific film from the second intensity and the third intensity, and calculates the film thickness calculated from the second intensity and the first film thickness. You may perform the process which determines whether the difference with the film thickness computed from three intensity | strengths is in a predetermined range.

  As described in detail above, in the present embodiment, the X-ray analyzer calculates the first intensity of the peak due to each element by peak separation, and then limits the change in peak intensity, and in a narrow energy range. Perform peak separation again. By limiting the energy range, it is possible to perform more detailed peak separation processing by focusing on high-intensity peaks used for concentration calculation among a plurality of peaks attributed to each element. Further, the first intensity obtained by normal peak separation is expected to be close to the accurate peak intensity, if not strictly accurate. Therefore, accurate peak separation can be performed by performing detailed peak separation processing while limiting the change so that the peak intensity takes a value close to the first intensity.

  In the present embodiment, the X-ray analyzer calculates the concentration of each element from the second intensity of the peak obtained by detailed peak separation, and a plurality of elements attributed to each element based on the calculated concentration. The third intensity of the peak is calculated by calculating the intensity ratio of the peak and performing peak separation using the calculated intensity ratio. The intensity ratio calculated here reflects the influence of a coexisting element in which each of a plurality of peak intensities resulting from one element changes according to the concentration of the coexisting element. In the peak separation using the intensity ratio of a plurality of peaks caused by each element calculated from the element concentration, a more probable peak intensity is obtained as the third intensity compared to the peak separation using the assumed intensity ratio. It is expected. In addition, since peak separation is performed in a wide energy range that includes multiple peaks attributed to one element, two elements that overlap in a limited energy range used for concentration calculation also overlap. Peak separation based on other peaks that are not present becomes possible, and it is expected that a probable peak intensity can be obtained as the third intensity. Furthermore, when a probable peak intensity is obtained, the process is returned, and the peak intensity can be calculated by repeating the detailed peak separation limiting the energy range after limiting the change in peak intensity. There is expected. By repeating the process until the fluctuation of the peak intensity or the concentration becomes sufficiently small, the concentration of each of the plurality of elements contained in the sample S can be calculated more accurately than before. Therefore, for a sample containing a plurality of elements in a combination that has conventionally been difficult to obtain an accurate concentration individually because peaks overlap in a specific energy range, such as a sample containing arsenic and lead, Quantitative analysis of elements can be performed more accurately than before. For example, when performing a quantitative analysis of harmful substances contained in the sample S, it becomes possible to distinguish arsenic and lead and perform a quantitative analysis with high accuracy. Even when the sample S has a complicated structure, such as when the sample S is a multilayer film, it is possible to perform quantitative analysis with high accuracy by distinguishing each element.

  Further, in the present embodiment, when the process is repeated, the X-ray analyzer can limit the change in peak intensity and omit detailed peak separation with a limited energy range and repeat the process. Analyze samples that are unlikely to be able to calculate peak intensity more accurately with detailed peak separation with limited energy range, for example because peaks of multiple elements are completely overlapped within a limited energy range. In this case, the processing time can be shortened by omitting detailed peak separation processing. Further, in the X-ray analyzer, since it is possible to set whether or not to omit detailed peak separation processing, it is possible to perform appropriate analysis according to the sample or element to be analyzed.

  The X-ray analyzer may be configured to always return the process to step S8 when looping the process, or may be configured to always return the process to step S9. Further, in step S8, the X-ray analysis apparatus does not limit the energy range, and the CPU 31 executes the upper peak separation in which the change in peak intensity caused by each element is limited within the energy range equivalent to step S7. Form may be sufficient. Further, the X-ray analysis apparatus may be configured such that the CPU 31 performs peak separation on the spectrum in which the energy range is limited without limiting the change in peak intensity in step S8. Depending on the composition of the sample S, qualitative / quantitative analysis is possible even in these forms.

  In the present embodiment, the X-ray spectrum measurement and the information processing are continuously performed. However, the X-ray analyzer temporarily stores the measured spectrum data. The information processing may be performed in the form. In this form, the X-ray analysis apparatus may perform processing for accepting settings necessary for information processing at the time of information processing. In the present embodiment, the X-ray analyzer has a function of measuring a fluorescent X-ray spectrum, but the X-ray analyzer does not have a function of measuring a fluorescent X-ray spectrum. Form may be sufficient. For example, the X-ray analysis apparatus may be configured by only the information processing apparatus 3 illustrated in FIG. In this mode, the X-ray analyzer receives the spectrum data of fluorescent X-rays measured by another device, and performs X-ray analysis on the input spectrum. In the present embodiment, the characteristic X-ray is a fluorescent X-ray. However, the X-ray analyzer is a characteristic X-ray generated from a sample irradiated with radiation other than X-rays such as an electron beam. The form which performs X-ray analysis with respect to the spectrum of may be sufficient.

11 X-ray source (irradiation unit)
12 X-ray detection unit 21 Spectrum generation unit 22 Control unit 3 Information processing device 31 CPU
32 RAM
34 storage unit 35 operation unit 36 display unit 4 recording medium 41 computer program S sample

Claims (9)

In an X-ray analyzer for determining the concentration of a plurality of elements contained in the sample based on a characteristic X-ray spectrum generated from the sample,
An intensity ratio specifying unit that sets an intensity ratio of a plurality of peaks caused by each element to a predetermined value;
A first intensity calculator that calculates a first intensity of each element peak included in the spectrum of the characteristic X-ray by performing peak separation using the intensity ratio;
The second intensity for calculating the second intensity of the peak of each element by limiting the change of the peak intensity from the first intensity within a predetermined range and performing peak separation for the specific energy range of the spectrum. A calculation unit;
A concentration calculator that calculates the concentration of a plurality of elements contained in the sample based on the second intensity of the peak of each element;
Based on the concentration of the plurality of elements calculated by the concentration calculation unit, an intensity ratio respecifying unit that calculates the intensity or intensity ratio of a plurality of peaks attributed to each element;
A third intensity calculation unit for calculating a third intensity of the peak of each element included in the spectrum by performing peak separation using the intensity or the intensity ratio calculated by the intensity ratio respecifying unit;
A determination unit that determines whether the difference between the second intensity and the third intensity, or the difference between the quantitative values of the specific types of amounts obtained from the second intensity and the third intensity is within a predetermined range;
Concentration determination for determining a concentration of a plurality of elements included in the sample to a concentration calculated by the concentration calculation unit when a difference between the second intensity and the third intensity or a difference between the quantitative values is within a predetermined range. And an X-ray analyzer. The second intensity calculator is
The X-ray analyzer according to claim 1, wherein a change in peak intensity is limited so that a magnification ratio of the peak intensity compared to the first intensity falls within a non-negative predetermined range. When the difference between the second intensity and the third intensity or the difference between the quantitative values is outside the predetermined range, the third intensity calculated by the third intensity calculator is set as the first intensity to the second intensity calculator. The X-ray analyzer according to claim 1, further comprising a first intensity specifying unit that returns the calculation. When the difference between the second intensity and the third intensity or the difference between the quantitative values is outside the predetermined range, the third intensity calculated by the third intensity calculator is set as the second intensity, and the concentration calculator is calculated. The X-ray analyzer according to claim 1, further comprising a second intensity specifying unit to be returned. A setting unit for setting whether to return the calculation to the second intensity calculation unit or the concentration calculation unit when the difference between the second intensity and the third intensity or the difference between the quantitative values is outside a predetermined range;
The third intensity calculation is performed when the setting unit is set to return the calculation to the second intensity calculation unit, and the difference between the second intensity and the third intensity or the difference between the quantitative values is outside a predetermined range. A first intensity specifying unit that returns the calculation to the second intensity calculating unit, with the third intensity calculated by the unit as the first intensity;
When the setting unit is set to return the calculation to the concentration calculation unit, and the difference between the second intensity and the third intensity, or the difference between the quantitative values is outside a predetermined range, the third intensity calculation unit The X-ray analysis apparatus according to claim 1, further comprising: a second intensity specifying unit that uses the calculated third intensity as the second intensity and returns the calculation to the concentration calculation unit. An irradiation unit for irradiating the sample with radiation; and
An X-ray detector for detecting characteristic X-rays generated from the sample;
The X-ray analysis apparatus according to claim 1, further comprising: a spectrum generation unit that generates a spectrum of characteristic X-rays detected by the X-ray detection unit. In a computer program for causing a computer to execute processing for obtaining concentrations of a plurality of elements contained in the sample based on a spectrum of characteristic X-rays generated from the sample,
On the computer,
A step of setting the intensity ratio of a plurality of peaks caused by each element to a predetermined value;
Calculating peak first intensity of each element included in the spectrum of characteristic X-ray by performing peak separation using the intensity ratio;
The second intensity for calculating the second intensity of the peak of each element by limiting the change of the peak intensity from the first intensity within a predetermined range and performing peak separation for the specific energy range of the spectrum. A calculation step;
A concentration calculating step for calculating concentrations of a plurality of elements contained in the sample based on the second intensity of the peak of each element;
Calculating an intensity ratio of a plurality of peaks caused by each element based on the calculated concentration of the plurality of elements;
Calculating a third intensity of a peak of each element included in the spectrum by performing peak separation using the calculated intensity ratio;
Determining whether the difference between the second intensity and the third intensity, or the difference between the quantitative values of the specific types of amounts obtained from the second intensity and the third intensity is within a predetermined range;
Determining a concentration of a plurality of elements contained in the sample to a concentration calculated in the concentration calculating step when a difference between the second intensity and the third intensity or a difference between the quantitative values is within a predetermined range; A computer program for executing a process including: On the computer,
When the difference between the second intensity and the third intensity or the difference between the quantitative values is outside the predetermined range, the process further includes a step of setting the third intensity as the first intensity and returning the process to the second intensity calculating step. The computer program according to claim 7, wherein the computer program is executed. On the computer,
When the difference between the second intensity and the third intensity or the difference between the quantitative values is outside the predetermined range, the process further includes a step of setting the third intensity as the second intensity and returning the process to the concentration calculating step. The computer program according to claim 7, wherein:

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