JP2011043402A - X-ray spectrum display processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the visibility of the X-ray spectrum displayed on a wavelength dispersion type X-ray analyzer using a plurality of spectral crystals and to facilitate the comparative evaluation with the X-ray spectrum obtained by an energy dispersion type X-ray analyzer. <P>SOLUTION: An appropriate changeover wavelength is set within a wavelength range, on which a spectral range is overlapped, with respect to the X-ray spectra corresponding to the respective spectral crystals (LiF, PET or the like) and spectrum data are respectively selected before and after the setting of the appropriate changeover wavelength. By this constitution, the spectrum to the same wavelength is determined uniquely. Further, the wavelength graduation interval of the respective measuring wavelength ranges is appropriately set according to the wavelength width or wavelength resolving power of the spectral range of the spectral crystals. A wavelength axis is compressed on the side of a long wavelength low in wavelength resolving power. By this constitution, the display widths of the measuring wavelength ranges corresponding to the respective spectral crystals become almost the same on a graph and, since the gradation interval does not also change extremely, the X-ray spectrum of high visibility reduced in the feeling of physical disorder of an analyst is obtained. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is an electron beam microanalyzer, a scanning electron microscope, a fluorescent X-ray analyzer, etc., which emits characteristic X-rays from a sample using an electron beam or X-ray as an excitation ray, and wavelength-disperses this by spectral crystal The present invention relates to a wavelength dispersion type X-ray analyzer that detects X-rays of a specific wavelength, and more particularly to a display processing device for displaying an X-ray spectrum acquired by such an X-ray analyzer.

  In elemental analysis using an electron beam microanalyzer (hereinafter referred to as “EPMA”), when an accelerated electron beam is irradiated on the sample surface as an excitation beam, the transition of core electrons of the contained elements of the sample occurs. Characteristic X-rays emitted to the outside are detected by a wavelength dispersion type X-ray spectrometer. Qualitative analysis is an analysis method for identifying the type of element contained in a sample from the peak wavelength and X-ray intensity of a characteristic X-ray spectrum obtained by scanning the wavelength of this X-ray spectrometer.

  EPMA can generally analyze a wide range of elements ranging from beryllium Be (atomic number 4) to uranium U (atomic number 92). However, due to structural limitations of the X-ray spectrometer, all of the above elements cannot be analyzed using one X-ray spectrometer. Therefore, EPMA is usually equipped with a plurality of X-ray spectrometers, and each X-ray spectrometer is equipped with different types of spectral crystals (spectral wavelength range and wavelength resolution) (see Patent Document 1, etc.). . By using a combination of these X-ray spectrometers as appropriate, qualitative analysis can be performed for all or most of the above elements.

  In the EPMA as described above, X-ray spectra in different wavelength ranges are obtained for each X-ray spectrometer. Therefore, when performing a qualitative analysis on various elements, an analyst needs a plurality of different wavelength ranges and wavelength resolutions. It is necessary to evaluate the X-ray spectrum. Therefore, in this type of conventional apparatus, a plurality of X-ray spectra obtained corresponding to a plurality of X-ray spectrometers can be displayed side by side on the same screen. FIG. 5 is an example of such a display. From the top, the spectroscopic crystals are LiF, PET (Penta erythritol), RAP (Rubidium Acid Phthalate), and PbST (lead stearate). It is a line spectrum.

  In the case of parallel display as shown in FIG. 5, the vertical axis range of one X-ray spectrum is narrow, and it is difficult to read the numerical value of the X-ray intensity. On the other hand, as another conventional display example, as shown in FIG. 6, a plurality of wavelength axes-intensity axes are provided in one graph, and four X-ray spectra are superimposed (actually, display of each spectrum). Some draw (with different colors).

  By the way, in other types of analyzers different from wavelength dispersion type X-ray analyzers, it is often possible to analyze almost all elements with one detector. Information on all analytical elements is reflected. For example, an analyzer using an energy dispersive X-ray analyzer (for example, an energy dispersive X-ray analyzer) can measure an X-ray spectrum in an energy range that covers all analysis elements. FIG. 7 is an example of such an X-ray spectrum. Although this type of analyzer has a low energy resolution, the peaks of all the elements appear in one X-ray spectrum, so that the evaluation during qualitative analysis of various elements is easy.

  On the other hand, in the display results shown in FIG. 5 and FIG. 6, as described above, it is necessary for the analyst himself to comprehensively evaluate a plurality of X-ray spectra having different measurement wavelength ranges and wavelength resolutions, which is difficult to see. It also takes time to work. In addition, when cross-checking the EPMA analysis result and the energy dispersive X-ray analysis result for the same sample, the EPMA display results shown in FIG. 5 and FIG. And oversight and mistakes are likely to occur.

JP 2008-26251 (FIG. 1, paragraphs [0018] to [0021])

  The present invention has been made to solve the above-mentioned problems, and its object is to improve the visibility of an X-ray spectrum obtained by a wavelength dispersion X-ray analyzer such as EPMA and to disperse energy. The present invention provides an X-ray spectrum display processing device that enables display that can be easily compared with a spectrum obtained by another analyzer such as a type X-ray analyzer.

In order to solve the above-mentioned problems, the present invention uses one or a plurality of X-ray spectrometers equipped with a plurality of spectral crystals having different spectral characteristics, and a measurement wavelength range and wavelength resolution for one sample. In an X-ray analyzer that acquires a plurality of X-ray spectra having different X-ray spectra, an X-ray spectrum display processing device for processing and displaying the plurality of X-ray spectra,
a) Overlapping for selecting one of the overlapping X-ray spectra according to the switching wavelength by setting a switching wavelength for linking the X-ray spectrum within the overlapping measurement wavelength range for the plurality of X-ray spectra Range processing means;
b) wavelength axis setting means for setting the wavelength scale interval of the wavelength axis according to the measurement wavelength range and / or wavelength resolution for each wavelength range of the X-ray spectrum corresponding to the spectral crystal;
c) Graph forming means for drawing a plurality of X-ray spectra obtained by processing the overlap range data by the overlap range processing means on a graph having a wavelength axis for which wavelength scale intervals are set by the wavelength axis setting means. When,
It is characterized by having.

  In the X-ray analyzer, one spectroscopic crystal is mounted on one X-ray spectrometer, and the same number of X-ray spectrographs as the number of types of spectroscopic crystals may be provided. Two or more spectroscopic crystals may be mounted so as to be mechanically interchangeable. In any case, it is possible to acquire the same number of X-ray spectra as the spectral crystals having different spectral characteristics.

  In general, the spectra overlap in a part of the X-ray spectrum corresponding to two spectral crystals covering the adjacent measurement wavelength range (the end of the measurement wavelength range). Therefore, the overlapping range processing means sets the switching wavelength within the overlapping wavelength range, and selects one spectrum in each of the wavelength ranges before and after the switching wavelength. For example, the switching wavelength can be determined so as to select the higher sensitivity of the two overlapping spectra. In the case of a compound crystal used in EPMA, a higher sensitivity can be obtained on the short wavelength side in principle in terms of structure. By executing the processing by the overlap range processing means, one of a plurality of data existing for the same wavelength is excluded.

  The wavelength axis setting means sets a wavelength scale interval corresponding to at least one of the measurement wavelength range and the wavelength resolution for each wavelength range of the X-ray spectrum corresponding to the spectral crystal. For example, based on the ratio of wavelength resolution determined by the lattice spacing of each spectral crystal, the wavelength width per wavelength scale interval is set to be larger as the wavelength resolution is lower. Usually, since the wavelength resolution becomes lower on the long wavelength side, the wavelength width with respect to the same wavelength scale interval becomes larger (that is, coarser) as the wavelength becomes longer. Further, the wavelength scale intervals may be set so that the widths of the measurement wavelength ranges for the spectral crystals displayed on the graph are approximately the same.

  The graph forming means draws a plurality of X-ray spectra on the graph having the wavelength axis in which the wavelength scale interval is set as described above, and thus, for example, covers a wide wavelength range almost covering all the elements that can be analyzed. An easy-to-see X-ray spectrum can be created.

  One embodiment of the present invention can be configured as follows. In other words, various types of spectral crystals are used, but the spectral range and wavelength resolution of each spectral crystal are known. Therefore, the spectral range and wavelength resolution are considered for various combinations of spectral crystals. Then, appropriate switching wavelengths and wavelength scale intervals are determined in advance and stored in a database. Then, the overlap range processing unit and the wavelength axis setting unit may use the database by deriving the switching wavelength and the wavelength scale interval from the combination of the spectral crystals used for the analysis. Thereby, it is possible to display an easy-to-view X-ray spectrum by a simple process without complicated judgment.

  According to the X-ray spectrum display processing apparatus according to the present invention, a plurality of X-ray spectra obtained for the same sample by the wavelength dispersive X-ray analyzer are aggregated and obtained by, for example, the energy dispersive X-ray analyzer. One X-ray spectrum over a wide wavelength range covering almost all elements that can be analyzed can be displayed on the screen. At that time, the wavelength axis is not linear, and is appropriately reduced or enlarged according to the characteristics of each spectroscopic crystal, etc., so that the peak wavelength interval is narrow and narrow while checking the entire X-ray spectrum at a glance. Each peak can be clearly displayed even in the wavelength range. As a result, the work efficiency of qualitative analysis using the X-ray spectrum is improved, particularly in the case where the analysis result of the wavelength dispersion X-ray analyzer and the analysis result of the energy dispersion X-ray analyzer are cross-checked. , X-ray spectrum comparison can be facilitated, and errors in evaluation and judgment can be reduced.

The block diagram of the principal part of EPMA using the display processing apparatus which is one Example of this invention. The processing flowchart in the display processing apparatus of a present Example. The figure which shows the example of the spectral range and wavelength resolution of a spectral crystal. The figure which shows the example of a display of the some X-ray spectrum by a present Example. The figure which shows the example of a display of the some X-ray spectrum in conventional EPMA. The figure which shows another example of a display of the some X-ray spectrum in conventional EPMA. The figure which shows the example of a X-ray spectrum display in an energy dispersive X-ray analyzer.

  An embodiment of an X-ray spectrum display processing apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a main part of an EPMA using an X-ray spectrum display processing apparatus according to this embodiment.

  In FIG. 1, an electron beam E as an excitation beam emitted from an electron gun 1 passes through a magnetic field formed by a deflection coil 2, is converged to a minute diameter by an objective lens 3, and is placed on a sample stage 4. S is irradiated. Thereby, characteristic X-rays are emitted from the surface of the sample S to the surroundings. A plurality of X-ray spectrometers are arranged above the sample S so as not to interfere with each other. In this figure, only two X-ray spectrometers 6a and 6b are depicted, but there are a total of four X-ray spectrometers (X-ray spectrometers not shown are denoted by 6c and 6d) so as to surround the sample S. It is arranged.

  Each of the X-ray spectrometers 6a to 6d includes a spectral crystal 61a (61b to 61d), an X-ray detector 63a (63b to 63d), and a slit 64a (64b to 64d), and is emitted from the sample S. Characteristic X-rays are wavelength-dispersed by the spectral crystals 61a to 61d, and diffracted X-rays having specific wavelengths pass through the slits 64a to 64d and are detected by the X-ray detectors 63a to 63d. For example, in the X-ray spectrometer 6a, the electron beam irradiation position on the sample S, the spectroscopic crystal 61a, and the X-ray detector 63a are always located on a Roland circle (not shown), and the spectroscopic crystal 61a is crystallized by a driving mechanism (not shown). The X-ray detector 63a is tilted while moving on the moving straight line 62a, and the X-ray detector 63a is rotated as shown in FIG. As a result, the X-ray wavelength scanning of the analysis object is achieved so that the diffraction condition of black is satisfied, that is, the incident angle of the characteristic X-ray and the emission angle of the diffracted X-ray with respect to the spectral crystals 61a and 61b are maintained equal. Is done. The configuration of the X-ray spectrometer is not limited to this, and various conventionally known configurations can be adopted.

  X-ray intensity detection signals from the X-ray detectors 63a to 63d are input to the data processing unit 8 in parallel, and the data processing unit 8 creates an X-ray spectrum corresponding to the wavelength scanning. The sample stage 4 can be moved in the horizontal plane by the sample stage driving unit 5, and the irradiation position of the electron beam E can be scanned on the sample S. Further, the magnetic field formed by the deflection coil 2 is changed by the drive current supplied from the deflection coil control unit 7, whereby the electron beam E is bent and the irradiation position on the sample S is shifted. As described above, the electron beam irradiation position (that is, the minute analysis position) on the sample S can be two-dimensionally scanned by either driving the sample stage 4 or driving the deflection coil 2.

  The analysis control unit 9 controls the operations of the sample stage driving unit 5, the X-ray spectrometers 6a to 6d, the deflection coil control unit 7, the data processing unit 8, and the like in order to perform analysis on the sample S. The central control unit 10 is connected to an operation unit 12 for giving an instruction by an analyst and a display unit 13 for providing information to the analyst, and has a function of setting analysis conditions and outputting analysis results. Usually, all or a part of the central control unit 10, the data processing unit 8, and the analysis control unit 9 are constituted by a personal computer (PC) and execute dedicated control / processing software installed in the PC. Can be used to achieve each function.

  The central control unit 10 includes a function corresponding to the display processing apparatus according to the present invention as the display processing unit 11. The operation of the display processing unit 11 can also be achieved by executing a program included in the control / processing software. Hereinafter, characteristic processing operations centered on the display processing unit 11 will be described with reference to FIGS.

  FIG. 3 shows the types of the four spectral crystals 61a to 61d used in the EPMA, the spectral range (measurement wavelength range), the wavelength resolution, and the like. The spectral crystals 61a to 61d are the above-described four types of LiF, PET, RAP, and PbST, and thus cover almost all analytical elements. That is, the X-ray spectrometer 6a to 6d equipped with these spectral crystals 61a to 61d performs X-ray analysis on a predetermined position on the sample S while performing wavelength scanning over the spectral range. For example, spectrum data constituting an X-ray spectrum for four different measurement wavelength ranges shown in FIG. 5 can be acquired.

  The display processing unit 11 aggregates the spectrum data obtained for each of the plurality of measurement wavelength ranges as described above, and has a full wavelength (energy) range as obtained by the energy dispersive X-ray analyzer shown in FIG. 7, for example. A process of creating and drawing one X-ray spectrum over a range of.

  As shown in FIG. 3, there is an overlapping portion in the spectral range of each spectral crystal. For example, in LiF and PET, the wavelength range of 0.26 to 0.38 nm overlaps, and as can be seen in FIG. 5, the spectrum data is present in any of two different X-ray spectra in this overlap range. Exists. In many cases, the intensity values of two spectral data at the same wavelength position are not the same. Therefore, if an X-ray spectrum of each spectral crystal is simply displayed on the same graph, two X-ray spectra in the overlapping range. Is displayed, and the graph becomes very difficult for an analyst to see and use.

  On the other hand, as shown in FIG. 3, it can also be seen that the wavelength resolution of each spectral crystal becomes lower (rougher) as it goes to the longer wavelength (low energy) side with respect to LiF having the highest wavelength resolution. The difference in wavelength resolution is up to about 25 times. Moreover, the wavelength range of the spectral range of each spectral crystal is also greatly different. Therefore, if each X-ray spectrum is displayed on the same graph using a linear wavelength axis in a wavelength range (for example, 0.1 to 10 nm) that covers the entire spectral range, the X-ray corresponding to each spectral crystal. The display width of the spectrum greatly differs in proportion to the wavelength range of the spectral range, and as a result, the graph becomes very difficult to see. Specifically, it becomes a graph with a very large width that requires the use of a horizontal scroll function or the like when displaying, or a graph that is so complicated that a plurality of peaks cannot be distinguished on the short wavelength side. .

  Therefore, the display processing unit 11 executes data processing according to the flowchart shown in FIG. 2 to finally create a graph that is easy to see and use for the analyst.

  First, the display processing unit 11 acquires spectral data corresponding to each of the spectral crystals 61a to 61d from the data processing unit 8 (step S1). This spectrum data may be data acquired by a new analysis, or may be data that has been analyzed in the past and saved in the data processing unit 8 or in a storage device outside thereof. In any case, spectral data corresponding to each of the spectroscopic crystals 61a to 61d obtained by analyzing one sample is obtained.

  As described above, in LiF and PET, and PET and RAP, there is an overlapping range in which spectral data overlap. Therefore, a process for switching the selection of two spectrum data with the switching wavelength as a boundary is set as an appropriate wavelength position within the overlap range (step S2).

  Preferably, the data with better sensitivity is selected from two spectral data corresponding to different spectral crystals. In general, in the overlap range where the spectral ranges overlap in EPMA, the spectral crystal on the short wavelength side has better sensitivity. In addition, it is not preferable to set the switching wavelength in the vicinity of the peak appearance position on the spectrum. Therefore, for example, in the overlap range between LiF and PET, 0.3 nm is set as the switching wavelength, spectrum data corresponding to LiF is adopted in a range below this wavelength, and spectrum data corresponding to PET in a longer wavelength range. Is adopted. Moreover, in the overlap part of PET and RAP, the switching wavelength is 0.8 nm, spectral data corresponding to PET is adopted in a range below this wavelength, and spectral data corresponding to RAP is adopted in a longer wavelength range. Like to do. Thereby, even in the overlap range, there is one spectral data for one wavelength position.

Next, the display processing unit 11 determines a wavelength scale interval for each display wavelength range of the spectrum corresponding to each of the spectral crystals 61a to 61d determined with the switching wavelength as a boundary (step S3). That is, as described above, in order to reduce the difficulty in viewing the graph due to the difference in wavelength resolution of the spectral crystals 61a to 61d and the wavelength width of the spectral range, basically, as the wavelength resolution decreases, the wavelength scale interval becomes smaller. The wavelength scale interval is determined so that the wavelength width is increased. In this example, in the case of the combination of the above four types of spectral crystals, the wavelength scale interval is determined in advance as follows in consideration of the resolution and spectral range of each spectral crystal.
・ LiF: 0.01 nm
・ PET: 0.02 nm
・ RAP: 0.1 nm
・ PbST: 0.5 nm

  If the wavelength scale interval is determined, a process of drawing a spectrum based on the spectrum data of each X-ray spectrum after data selection in step S2 for one graph frame whose wavelength axis is set to the wavelength scale interval (Step S4). At this time, the display color of the X-ray spectrum is changed for each spectral crystal. As a result, a graph as shown in FIG. 4 is created and displayed on the screen of the display unit 13.

  As is apparent from FIG. 4, the wavelength ranges corresponding to the four types of spectral crystals have approximately the same horizontal width on the graph. Further, the interval between the scales of the wavelength axis is not extremely narrow or wide, and is easy to see. Further, as shown in FIG. 5, the peak width is wide because the wavelength resolution is originally low on the long wavelength side (for example, PbST), but in the display of FIG. 4, the wavelength axis is compressed on the long wavelength side. Therefore, the peak is apparently expressed as a linear peak with a narrow width. For this reason, there is also an attendant effect that an X-ray spectrum with less discomfort for the analyst can be obtained.

  Note that the graph shown in FIG. 4 is obtained by directly displaying the spectral data corresponding to each spectral crystal as a graph, so the spectrum is discontinuous at the switching wavelength (eg, 0.3 nm), but the background is removed. If the baseline of each spectrum is made substantially zero by performing the processing, it is possible to obtain a substantially continuous spectrum before and after the switching wavelength. Further, although there is a blank wavelength range (2.45 to 2.8 nm) where no spectrum data exists between RAP and PbST, the spectrum appears to be continuous even in this range.

The numerical values of the switching wavelength and the wavelength display scale interval given in the above description are examples. For example, the above-mentioned wavelength display scale interval is determined with emphasis on the difference in the spectral range rather than the difference in wavelength resolution, but it may be determined as follows with an emphasis on the difference in wavelength resolution. Good.
-LiF: 0.025nm
・ PET: 0.05nm
・ RAP: 0.15 nm
・ PbST: 0.75 nm
This is a one-wavelength display scale interval in PET, RAP, and PbST set to 2 times, 6 times, and 30 times, respectively, with reference to the 1 wavelength display scale interval in LiF.

  Moreover, in the said Example, although 4 types of spectral crystals, LiF, PET, RAP, and PbST, were used, Ge, TAP (Thallium Acid Phthate), EDDT (ethylenediaminetetraacetic acid), etc., Various things are used. Even in such a case, since the spectral range and wavelength resolution of the spectral crystal are known, a switching wavelength and a wavelength display graduation interval are determined in advance for a combination of various spectral crystals, and the above-described steps S2 and S3 are performed. It is practical to obtain the switching wavelength and the wavelength scale interval by referring to the database from the combination of the spectral crystals used.

  In the example shown in FIG. 4, the vertical axis is the X-ray intensity axis (absolute count value) common to each spectral crystal, but this may be a relative intensity. In addition, when the sensitivity is greatly different depending on the spectral crystal, a plurality of intensity scales may be used without sharing the intensity axis with each spectral crystal.

  Further, although the above embodiment has been described by taking EPMA as an example, the X-ray spectrum display processing apparatus according to the present invention uses a wavelength scanning X-ray analyzer using an X-ray spectrometer equipped with a plurality of spectral crystals. It is apparent that the present invention can be applied to other analyzers.

DESCRIPTION OF SYMBOLS 1 ... Electron gun 10 ... Central control part 11 ... Display processing part 12 ... Operation part 13 ... Display part 2 ... Deflection coil 3 ... Objective lens 4 ... Sample stage 5 ... Sample stage drive part 6a-6d ... X-ray spectrometer 61a- 61d ... Spectroscopic crystals 62a-62d ... Crystal movement straight lines 63a-63d ... X-ray detectors 64a-64d ... Slit 7 ... Deflection coil controller 8 ... Data processor 9 ... Analysis controller E ... Electron beam S ... Sample

Claims (2)

X-ray analysis for obtaining a plurality of X-ray spectra having different measurement wavelength ranges and wavelength resolutions for one sample using one to a plurality of X-ray spectrometers equipped with a plurality of spectral crystals having different spectral characteristics In the apparatus, an X-ray spectrum display processing device for processing and displaying the plurality of X-ray spectra,
a) Overlapping for selecting one of the overlapping X-ray spectra according to the switching wavelength by setting a switching wavelength for linking the X-ray spectrum within the overlapping measurement wavelength range for the plurality of X-ray spectra Range processing means;
b) wavelength axis setting means for setting the wavelength scale interval of the wavelength axis according to the measurement wavelength range and / or wavelength resolution for each wavelength range of the X-ray spectrum corresponding to the spectral crystal;
c) Graph forming means for drawing a plurality of X-ray spectra obtained by processing the overlap range data by the overlap range processing means on a graph having a wavelength axis for which wavelength scale intervals are set by the wavelength axis setting means. When,
An X-ray spectrum display processing device comprising: The X-ray spectrum display processing device according to claim 1,
For various combinations of spectral crystals that can be used, a database for storing a switching wavelength and a wavelength scale interval predetermined for each combination is provided,
X-ray spectrum display processing characterized in that the overlap range processing means and the wavelength axis setting means derive a switching wavelength and a wavelength scale interval from a combination of spectral crystals used for analysis using the database. apparatus.

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