JP2006058015A - X-ray analyzer with wave height distribution display function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain in real time a wave height distribution of X-rays detected by WDS in an apparatus equipped with a wavelength dispersive X-ray spectrometer (WDS) and an energy dispersive X-ray spectrometer (EDS) at the same time. Enables easy setting of WDS wave height analyzer conditions.
A selector switch is provided so that an output signal from a signal processing circuit connected to an X-ray detector of a WDS can be input to a multichannel analyzer configured for EDS. After performing the matching processing necessary for inputting the output of the signal processing circuit of the WDS to the multi-channel analyzer, the multi-channel analyzer discriminates the wave height and integrates it. The wave height distribution is displayed on the EDS spectrum display device. When the conditions of the WDS wave height analyzer are set from the displayed wave height distribution, the conditions of the single channel analyzer configured for WDS are automatically set.
[Selection] Figure 2

Description

The present invention relates to an electron probe microanalyzer (EPMA) and a fluorescent X-ray analyzer (XRF) equipped with a wavelength dispersive X-ray spectrometer (WDS) and an energy dispersive X-ray spectrometer (EDS) at the same time. The present invention relates to a method of displaying a wave height distribution of an X-ray signal detected by a distributed X-ray spectrometer (WDS).

A method of performing elemental analysis by detecting characteristic X-rays generated by irradiating a substance with electrons or X-rays is widely used in EPMA and XRF.
Methods for detecting characteristic X-rays are roughly classified into a wavelength dispersive X-ray spectrometer (WDS) using a spectroscopic element and an energy dispersive X-ray spectrometer (EDS) using a semiconductor detector. EPMA and XRF are equipped with WDS or EDS, but since WDS and EDS have their respective functions and performances, many devices equipped with both WDS and EDS and controlled by a single computer system have been put into practical use. ing.

As an example of the above equipment, WDS and EDS are installed at the same time, and an X-ray measurement system consisting of an X-ray detector, a signal processing circuit, a pulse height analyzer, etc. is provided separately for WDS and EDS, and is shared by WDS / EDS. FIG. 1 shows a configuration example of an EPMA including the host computer system and a display device. The electron beam 2 generated from the electron gun 1 is narrowed down by an electron optical system (not shown) and irradiated to the analysis sample 3 to generate X-rays. X-rays detected by the EDS 4 are sent to the host computer 10 via the EDS signal processing device 6 and the EDS MCA 8. The X-rays detected by the WDS 5 are sent to the host computer 10 via the WDS signal processor 7 and the WDS SCA 9.
Here, MCA multichannel analyzer (MCA: M ulti C hannel A nalyzer), SCA single channel analyzer: an abbreviation for (SCA S ingle C hannel A nalyzer ).

Next, the role of SCA in WDS will be described. X-rays incident on the spectroscopic element in WDS are the following conditions called Bragg's law shown in FIG.
2d × sin θ = n × λ (1)
d: Spacing between spectral elements θ: X-ray incident angle and reflection angle λ: X-ray wavelength n: reflection order (1, 2,...)
X-rays that are diffracted satisfying the above are guided to the X-ray detector.
In WDS, a gas amplification type X-ray detector capable of extracting a current pulse having a peak value proportional to the energy of one incident X-ray quantum is often used. X-ray quanta incident on the X-ray detector ionize gas molecules to generate electron / ion pairs. Electrons ionized by the bias applied to the detector are amplified and taken out as current pulses. Since the number of electron / ion pairs that are initially ionized varies due to statistical fluctuations, even if the energy of incident X-rays is constant, the pulse peak value varies.
As can be seen from the equation (1), a high-order diffraction line having an energy that is an integral multiple of the X-ray is superimposed at a position where an X-ray having a certain wavelength is diffracted and detected. Therefore, if a characteristic X-ray diffracted by another element is superimposed as an interference line in the vicinity of the characteristic X-ray of the target element for analysis, set the wave height analyzer (PHA: Pulse Height Analyzer) correctly. Therefore, it is necessary to remove the interference signal from the detected X-ray signal.

The PHA has functions such as checking the height of the X-ray signal pulse and applying a filter. SCA plays this role in WDS, and is shown as SDS 9 for WDS in FIG. As the name suggests, SCA can set only one channel (ie, window) for selecting the peak value of the X-ray signal. In order to accurately set the PHA, it is necessary to measure the wave height distribution of the detected X-ray signal and set the conditions suitable for the wave height distribution. The concept of the setting method of the WDS SCA 9 will be described with reference to FIGS. As shown in FIG. 6, X-rays are scanned for each step while sequentially scanning with the step width set from the near zero to the maximum value while setting the window (= Upper level-Lower level) to an appropriately small width. Are counted and plotted. As shown in FIG. 7, the lower level and upper level are determined so that only the primary line falls within the window range by looking at the plotted wave height distribution. Electric noise having a peak value lower than the lower level and higher-order diffraction lines of the second or higher order are removed.

On the other hand, in EDS, one X-ray quantum incident on a semiconductor generates a number of electron / hole pairs proportional to the energy, and as a result, it is extracted as a current pulse having a peak value proportional to the energy. Since the pulse peak value is proportional to the energy of the incident X-ray, the X-ray spectrum can be obtained by selecting the amplified pulses of the X-ray quanta sequentially incident on the detector by MCA, and integrating and displaying them on the corresponding channel. It is done. FIG. 5 shows a display example of the X-ray spectrum detected by EDS. The horizontal axis is a channel corresponding to the energy of X-rays, usually having about 1000 channels, and a function for enlarging and displaying a part thereof. The vertical axis represents the integrated value of the detected X-ray quanta, and a device having a scale enlargement / reduction and an autoscale function is generally used.
JP 2002-357571 A JP-A-1-185480

As described above, in order to accurately set the WDS wave height analyzer, conventionally, the Lower Level is gradually raised from the vicinity of zero while setting the window of the SCA for WDS to an appropriately small width, and at each step. A method of counting the X-ray intensity has been performed. This method requires knowledge and experience to determine the width of windows and steps and the counting time for each step, and takes time to measure because counting is performed for each step. For this reason, even a skilled person sometimes has to take the time to obtain the wave height distribution and then change the conditions again to obtain the wave height distribution again.

In order to solve the above problems, the present invention provides a wavelength dispersive X-ray spectrometer and an energy dispersive X-ray for irradiating a sample with an electron beam or X-ray to detect characteristic X-rays generated from the sample. In the X-ray analyzer simultaneously equipped with a spectrometer, the output signal from the signal processing circuit connected to the X-ray detector of the wavelength dispersive X-ray spectrometer is configured for the energy dispersive X-ray spectrometer. Switching means for inputting to the multi-channel analyzer, and display means for displaying the wave height distribution of the X-ray signal detected by the X-ray detector of the wavelength dispersive X-ray spectrometer on the display device of the X-ray analyzer It is characterized by comprising.

According to the present invention, the peak value of the X-ray signal detected by the X-ray detector of the wavelength dispersive X-ray spectrometer displayed on the display device of the X-ray analyzer by the multi-channel analyzer is used as the wavelength dispersive type. Means is provided for converting so as to show the same value as the peak value displayed by a single channel analyzer configured for an X-ray spectrometer.

Further, the present invention provides an input means from the wave height distribution of the X-ray signal detected by the X-ray detector of the wavelength dispersive X-ray spectrometer displayed on the display device of the X-ray analyzer by the multi-channel analyzer. A means for automatically setting the setting conditions of the wave height analyzer of the wavelength dispersive X-ray spectrometer is provided on the basis of the information of the lower level and the upper level set by use.

According to the present invention, there is provided a display device for displaying a wave height distribution of an X-ray signal detected by the X-ray detector of the wavelength dispersive X-ray spectrometer by the multi-channel analyzer. It is a display device shared by a dispersive X-ray spectrometer.

Further, the present invention provides a display device for displaying a wave height distribution of an X-ray signal detected by an X-ray detector of the wavelength dispersive X-ray spectrometer by the multi-channel analyzer, the display device for the energy dispersive X-ray spectrometer It is characterized by being.

According to the present invention, the wave height distribution of the X-ray signal detected by the X-ray detector of the wavelength dispersive X-ray spectrometer can be displayed on the display device by the multi-channel analyzer for energy dispersive X-ray spectrometer. The wave height distribution of the wavelength dispersive X-ray spectrometer can be easily obtained in real time.

Further, according to the present invention, based on the information of the lower level and the upper level determined from the wave height distribution of the wavelength dispersive X-ray spectrometer displayed by the multi-channel analyzer for energy dispersive X-ray spectrometer, the wavelength dispersive X-ray Since the setting conditions of the wave height analyzer of the spectrometer can be automatically set, even beginners can quickly and accurately set the wave height analyzer of the wavelength dispersive X-ray spectrometer.

Taking EPMA as an example, FIG. 2 shows a first embodiment of the present invention.
In the conventional configuration of FIG. 1, the signal level changer 12 and the signal matching device 13 for inputting the output signal from the WDS to the MCA configured for EDS, and the lower level from the wave height distribution of the WDS displayed by the MCA for EDS. An input device 14 for determining the upper level is added. The host computer 10 also supplies a command signal for setting the setting conditions of the WDS wave height analyzer to the WDS SCA 9 based on the Lower level and Upper level conditions input from the input device 14.
In the configuration of the first embodiment, the host computer 10 and the display device 11 are shared by WDS and EDS.

The operation of the first embodiment will be described with reference to FIG.
The signal switcher 12 is switched to the terminal A side during EDS measurement, and a signal from the EDS signal processing device 6 is sent to the EDS MCA 8. In response to a signal switching instruction from the host computer 10, the signal switching unit 12 is switched to the terminal B side. The signal from the WDS is adjusted by the signal matching device 13 so that the output of the WDS signal processing device 7 becomes a signal within the input allowable range of the EDS MCA 8 and sent to the EDS MCA 8.
The EDS MCA 8 identifies the wave height of the input signal, assigns it to the corresponding channel, and sequentially accumulates it. The host computer 10 converts the X-ray quantum number accumulated for each channel corresponding to the identified peak value into a bar height or the like, and displays it on the display device 11 as a peak height distribution in real time.

FIG. 8 shows an example in which the peak value of the signal from the WDS is displayed by the EDS MCA 8. The horizontal axis represents the crest value, and is converted and displayed by the host computer 10 so that the maximum / minimum value is the same as the scale of the SCA 9 for WDS. The vertical axis represents the integrated value of the X-ray signal. As the signal from the WDS is integrated into each channel, the corresponding bar increases in sequence. In FIGS. 5 and 8, a bar is used to represent the intensity on the vertical axis, but the present invention is not limited to this, and the intensity display in FIGS. 6 and 7 is also limited in any way. There is nothing.

FIG. 9 shows an example in which WDS SCA conditions are set by EDS MCA. Using the input device 14 such as a mouse, set the Lower level and Upper level so that the secondary line and electrical noise are removed from the wave height distribution displayed on the display device 11 and only the primary line is included in the window. specify. The specified Lower level and Upper level conditions are sent to the WDS SCA 9, and the Lower level and Upper level of the WDS SCA 9 are set by an instruction from the host computer 10. When the setting of the SCA is completed, the signal switcher 12 is switched again to the terminal A side according to an instruction from the host computer 10, and the signal from the WDS signal processor 7 is sent to the host computer 10 via the WDS SCA9. The signal from the EDS signal processing device 6 is also sent to the host computer 10 via the EDS MCA 8 and the EDS spectrum is displayed, so that analysis by WDS and EDS can be performed simultaneously.

Next, a second embodiment will be described based on FIG.
In the first embodiment of FIG. 2, the host computer 10 and the display device 11 share WDS and EDS, but in the second embodiment, WDS and EDS have separate host computers.
The EDS host computer 10-1 displays the identified peak value of the signal input from the WDS via the signal switcher 12 to the EDS MCA 8 on the display device 11 in real time as a pulse height distribution. The Lower level and Upper level setting values specified from the input device 14 are sent from the WDS host computer 10-2 to the EDS host computer 10-1, and displayed on the display device 11. The operator can appropriately observe this while watching this. The window setting conditions. The determined Lower level and Upper level setting values are sent from the WDS host computer 10-2 to the WDS SCA 9 and set in conditions. Other operations are the same as those in the first embodiment.

Next, a third embodiment will be described based on FIG.
In the first embodiment of FIG. 2, the host computer 10 and the display device 11 share the WDS and EDS, but in the third embodiment, the WDS and the EDS have separate host computers and display devices.
The EDS host computer 10-1 displays the identified peak value of the signal input from the WDS via the signal switch 12 to the EDS MCA 8 on the EDS display device 11-1 in real time as a pulse height distribution. The Lower level and Upper level setting values specified from the input device 14 are sent from the WDS host computer 10-2 to the EDS host computer 10-1, and displayed on the EDS display device 11-1. Determine the appropriate window setting conditions. The determined Lower level and Upper level setting values are sent from the WDS host computer 10-2 to the WDS SCA 9 and set in conditions. Other operations are the same as those in the first embodiment.

The example of a structure of the conventional apparatus which took EPMA as an example. The structural example which shows 1st Embodiment of this invention which took EPMA as an example. The structural example which shows 2nd Embodiment of this invention which took EPMA as an example. The structural example which shows the 3rd Embodiment of this invention which took EPMA as an example. The example which displays the X-ray spectrum taken by EDS by MCA. The figure for demonstrating the wave height distribution measurement by SCA of WDS. The figure for demonstrating the condition setting in SCA of WDS. The figure for demonstrating the example which displays the wave height distribution of WDS by MCA of EDS. The figure for demonstrating the example which sets the SCA condition of WDS from the wave height distribution displayed by MCA of EDS. The figure for demonstrating Bragg's law.

Explanation of symbols

(The same number is attached | subjected to the common thing about FIGS. 1-4.)
1: Electron gun 10: Host computer 2: Electron beam 10-1: EDS host computer 3: Analysis sample 10-2: WDS host computer 4: WDS 11: Display device 5: EDS 11-1: EDS display device 6: Signal processing device for EDS 11-2: Display device for WDS 7: Signal processing device for WDS 12: Signal switcher 8: MCA for EDS 13: Signal matching device 9: SCA for WDS 14: Input device

Claims (5)

In an X-ray analyzer equipped with a wavelength dispersive X-ray spectrometer and an energy dispersive X-ray spectrometer simultaneously for irradiating a sample with an electron beam or X-ray and detecting characteristic X-rays generated from the sample, Switching means for inputting an output signal from a signal processing circuit connected to the X-ray detector of the wavelength dispersive X-ray spectrometer to a multi-channel analyzer configured for the energy dispersive X-ray spectrometer; An X-ray analyzer comprising: display means for displaying a wave height distribution of an X-ray signal detected by an X-ray detector of the wavelength dispersive X-ray spectrometer on a display device of the X-ray analyzer . The peak value of the X-ray signal detected by the X-ray detector of the wavelength dispersive X-ray spectrometer displayed on the display device of the X-ray analyzer by the multi-channel analyzer is used for the wavelength dispersive X-ray spectrometer. 2. The X-ray analyzer according to claim 1, further comprising means for converting so as to show the same value as the peak value displayed by the configured single channel analyzer. Lower set by using input means from the wave height distribution of the X-ray signal detected by the X-ray detector of the wavelength dispersive X-ray spectrometer displayed on the display device of the X-ray analyzer by the multi-channel analyzer. The X-ray analysis according to claim 1, further comprising means for automatically setting a setting condition of a wave height analyzer of the wavelength dispersive X-ray spectrometer based on level and upper level information. apparatus. A display device for displaying a wave height distribution of an X-ray signal detected by an X-ray detector of the wavelength dispersive X-ray spectrometer by the multi-channel analyzer includes the wavelength dispersive X-ray spectrometer and the energy dispersive X-ray spectrometer. The X-ray analyzer according to claim 1, wherein the X-ray analyzer is a display device shared by the instrument. The display device that displays the wave height distribution of the X-ray signal detected by the X-ray detector of the wavelength dispersive X-ray spectrometer by the multichannel analyzer is a display device for the energy dispersive X-ray spectrometer. The X-ray analyzer according to claim 1, wherein

Images