X-ray spectrophotometer

Abstract

To provide a laboratory-type X-ray spectrometer that reduces background noise and enables more accurate X-ray absorption spectroscopy and / or X-ray fluorescence spectroscopy measurements. [Solution] The system comprises at least one of a two-dimensional Si detector 14 or a silicon drift detector 13, and a filter (10, 11) provided between the two-dimensional Si detector 14 and / or the silicon drift detector 13 and the spectroscopic crystal, including the irradiation region, wherein the filter is made of a metal, metal oxide, or alloy that satisfies 0.8 ≤ exp(-μρt) ≤ 2.0 in the range of 10 to 30 keV for the energy of the irradiated X-rays 8. (In the formula, μ is the mass attenuation coefficient (cm) of the metal element constituting the filter at a specific energy.) 2 ( / g), ρ is the density (g / cm³) of the metal elements constituting the filter. 3 ), where t represents the thickness of the filter (cm).

Description

[Technical Field]

[0001] This disclosure relates to an X-ray spectroscopic analyzer with reduced background noise, suitable for use in X-ray absorption spectroscopy (XAS) and / or X-ray emission spectrometry (XES) systems. [Background technology]

[0002] Synchrotron radiation, also known as X-ray sources, is electromagnetic radiation emitted in a direction along the previous direction of travel when high-energy electrons are deflected by a magnetic field from a bending electromagnet within a circular accelerator. Synchrotron radiation X-rays and laboratory X-rays are similar in that electrons are subjected to some form of bremsmädz (breathing) to generate X-rays, but their X-ray beam intensity per unit area differs significantly. In other words, synchrotron radiation has a 10-fold increase in intensity compared to an X-ray tube. 6 ~10 9 Synchrotron radiation has twice the brightness and high directivity in the direction of emission. Therefore, because synchrotron radiation has a higher signal-to-noise ratio (SNR) compared to X-ray tubes, it is suitable for precise physical property analysis. However, synchrotron radiation X-ray sources are far more expensive than laboratory-type X-ray sources, so laboratory-type X-ray sources are widely used for physical property analysis in normal laboratories that are not radiation-controlled areas.

[0003] In laboratory-type X-ray absorption spectroscopy systems, X-ray absorption spectroscopy measurements have been conventionally performed using a high-brightness X-ray source and a spectrometer made of a spectroscopic crystal such as germanium. Patent Document 1 discloses a method and system for simultaneously performing X-ray absorption spectroscopy and X-ray fluorescence spectroscopy analysis. Non-Patent Document 1 discloses how to reduce mechanical freedom in the design of X-ray absorption fine structure spectroscopy (XAFS) and X-ray fluorescence spectroscopy (XES) systems and achieve high-precision measurements in a wide-angle Bragg-angle type laboratory XAFS configuration.

[0004] Furthermore, in order to increase the signal-to-noise ratio (SNR) in a laboratory-type X-ray absorption apparatus, Patent Document 2 discloses a multi-X-ray generation method and an apparatus therefor, in which a metal material filter is disposed immediately after an X-ray source, and X-ray peaks are provided in a low-energy narrow band and / or a high-energy narrow band. Patent Document 3 discloses an X-ray filter that selectively transmits X-rays in a specific energy band among continuous X-rays, the X-ray filter comprising a glass member containing, as a composition, a plurality of types of elements each having a K absorption edge within an X-ray energy range of 35 keV or more and 47 keV or less. [Prior Art Documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No.2023-107744 [Patent Document 2] Japanese Patent No.4776212 [Patent Document 3] Japanese Patent No.4198030 [Non-Patent Documents]

[0006] [Non-Patent Document 1] “An improved laboratory-based x-ray absorption fine structure and x-ray emission spectrometer for analytical applications in materials chemistry research.” Rev. Sci. Instrum. 90, 024106, (2019) [Summary of the Invention] [Problems to be Solved by the Invention]

[0007] However, conventional laboratory-type X-ray sources have poor directivity in relation to the direction of X-ray emission compared to synchrotron radiation X-ray sources. As a result, fluorescence scattering from the X-ray source, fluorescence scattering from the spectroscopic crystal, and scattered light from the components of the device (mainly stainless steel containing Fe, Mn, Co, and Ni) and the surrounding atmosphere irradiates the sample and detector, leading to increased background noise and false signals in the detection signal. This disclosure aims to solve the above problems by providing a laboratory-type X-ray spectroscopic analyzer that reduces background noise, improves the signal-to-noise ratio (SNR), and enables more accurate X-ray absorption spectroscopy and / or X-ray fluorescence spectroscopy measurements. [Means for solving the problem]

[0008] The inventors conceived of this disclosure based on the idea that if stray X-rays could be filtered and shielded from fluorescence scattering from the X-ray source, fluorescence scattering from the spectroscopic crystal, and scattered light from the components of the laboratory-type X-ray spectrometer (mainly stainless steel containing Fe, Mn, Co, and Ni) and the surrounding atmosphere, background noise could be reduced, the signal-to-noise ratio could be improved, and more accurate XAS and XES spectral measurements could be made possible.

[0009] The X-ray spectrometer of the present disclosure comprises an X-ray source tube 1 for generating continuous X-rays, a spectroscopic crystal 7 for spectrally or monochromatically emitting the continuous X-rays, at least one of a two-dimensional Si detector 14 for detecting X-rays that have passed through a predetermined irradiation area on the surface of a sample after irradiating the X-rays spectrally or monochromatically emitting by the spectroscopic crystal, or a silicon drift detector 13 for detecting fluorescent X-rays scattered in the irradiation area, the two-dimensional Si detector 14 including the irradiation area, or the silicon drift detector 13 for detecting fluorescent X-rays scattered in the irradiation area, and filters (10, 11) provided between the spectroscopic crystals, wherein the filters (10, 11) are made of a metal, metal oxide, or alloy with a thickness that satisfies the following formula (1) when the energy of the irradiated X-rays 8 is in the range of 10 to 30 keV. 0.8≦exp(-μρt)≦2.0 …(1) In equation (1), μ is the mass attenuation coefficient (cm) of a metallic element at a specific energy. 2 ( / g), ρ is the density of the metallic element (g / cm³). 3 ), where t represents the thickness of the metal filter (cm). [Effects of the Invention]

[0010] According to the X-ray spectroscopic analyzer of this disclosure, by providing a stray X-ray shielding member, fluorescence scattering from the X-ray source, fluorescence scattering from the spectroscopic crystal, and scattered light from the components (mainly SUS) of the laboratory-type X-ray absorption spectrometer and the surrounding atmosphere of the detector can be shielded as stray X-rays, resulting in a high background reduction effect. Furthermore, according to the X-ray spectroscopic analyzer of this disclosure, an even higher background reduction effect can be obtained by providing a first X-ray filter and a second X-ray filter in addition to the stray X-ray shielding member. [Brief explanation of the drawing]

[0011] [Figure 1] This is a top view of the main body of an X-ray absorption / fluorescence spectrometer showing one embodiment of the present disclosure. [Figure 2] This is a system diagram of an X-ray absorption / fluorescence spectrometer showing one embodiment of the present disclosure. [Figure 3] Figure 2 illustrates the behavior of scattered light and scattered electrons in the apparatus shown. [Figure 4] This is a flowchart illustrating the absorption spectrum measurement process. [Figure 5] This figure shows an example of the background when the shield is applied. [Figure 6] This figure shows an example of background noise when only a Zn filter is applied, demonstrating that the Ge background was reduced to approximately 1 / 10. [Figure 7] The figure shows an example of background noise when a Zn+Cu filter is applied, indicating that the Ge background was reduced to approximately 1 / 100th. [Figure 8]This figure shows an example of filter (+shield) application, illustrating the results of X-ray absorption fine structure (XAFS) measurements using Cu foil as a sample. [Figure 9] The figure shows an example of shielding (+filter) application, and displays the results of X-ray absorption fine structure (XAFS) measurements using Ru foil as a sample. [Modes for carrying out the invention]

[0012] [Description of Embodiments in this Disclosure] First, embodiments of this disclosure will be listed and described. Note that the numerical ranges in this disclosure include upper and lower limits.

[0013] [1] The X-ray absorption spectrometer of the present disclosure, as shown in Figures 1 to 3, for example, comprises an X-ray source tube 1 for generating continuous X-rays, a spectroscopic crystal 7 for spectrally or monochromatically emitting the continuous X-rays, at least one of a two-dimensional Si detector 14 that detects X-rays that have passed through a predetermined irradiation area on the surface of a sample after irradiating the X-rays spectrally or monochromatically emitted by the spectroscopic crystal, or a silicon drift detector 13 that detects fluorescent X-rays scattered in the irradiation area, and filters (10, 11) provided between the two-dimensional Si detector 14 and / or the silicon drift detector 13 and the spectroscopic crystal, including the irradiation area, wherein if the metal element constituting the filter is a single element, it consists of a metal, metal oxide or alloy that satisfies the following formula (1) in the range of 10 to 30 keV for irradiation X-ray energies, and if the metal elements constituting the filter are multiple elements (i=1, 2, ..., n: n is a natural number of 2 or more), it consists of a metal, metal oxide or alloy that satisfies the following formula (2) in the range of 10 to 30 keV for irradiation X-ray energies. 0.8≦exp(-μρt)≦2.0 …(1) In equation (1), μ is the mass attenuation coefficient (cm) at a specific energy when the metal element constituting the filter is a single element. 2 ( / g), ρ is the density (g / cm³) of the metal elements constituting the filter. 3 ), where t represents the thickness of the filter (cm).

number

[0014] [2] In the X-ray spectroscopic analyzer [1] of the present disclosure, the filter 10 is preferably formed by arranging a Zn foil with a thickness of 5 μm or more and 15 μm or less and a Cu foil with a thickness of 5 μm or more and 15 μm or less in the X-ray optical path in the order of Zn foil-Cu foil based on the X-ray radiation direction, so that the characteristic X-ray fluorescence of Zn is attenuated by Cu. The filter preferably satisfies the following formula (3) when the energy of the irradiated X-ray is in the range of 10 to 30 keV. 0.5≦exp(-μ Zn ρ Zn t Zn -μ Cu ρ Cu t Cu )≦1.5 …(3) In formula (3), μ Zn and μ Cu are the mass attenuation coefficients (cm 2 / g) of Zn and Cu constituting the filter at a specific energy, ρ Zn and ρ Cu are the densities (g / cm 3 ) of Zn and Cu constituting the filter, and t Zn and t Cu represent the thicknesses (cm) of Zn and Cu of the filter, respectively. Here, "based on the X-ray radiation direction" intends the propagation direction of X-rays, since X-rays are irradiated from an X-ray source tube toward a target sample. [3] In the X-ray spectrometer [1] of the present disclosure, the filter 11 is preferably configured such that a Ti foil with a thickness of 3 μm to 5 μm and an Al foil with a thickness of 20 μm to 400 μm are arranged in the X-ray optical path in the order of Ti foil-Al foil with respect to the X-ray emission direction, and the characteristic X-ray fluorescence of Ti is attenuated by the Al foil, and the filter preferably satisfies the following equation (4) in the range of irradiation X-ray energy of 10 to 30 keV. 0.5 ≤ exp(-μ) Ti ρ Ti t Ti -μ Al ρ Al t Al ) ≤ 1.5 …(4) In formula (4), μ Ti , μ Al The mass attenuation coefficient (cm) of Ti and Al, which constitute the filter, at specific energies. 2 / g), ρ Ti ρ Al The density (g / cm³) of Ti and Al that constitute the filter is the density of the Ti and Al that make up the filter. 3 ), t Ti t Al The value (cm) represents the thickness of the Ti and Al in the aforementioned filter. [4] In the X-ray spectrometer [1] of the present disclosure, the filters (10, 11) include a first filter 10 and a second filter 11 located downstream of the spectroscopic crystal 7. The first filter 10 is configured to attenuate the characteristic X-ray fluorescence of Zn by Cu by arranging a Zn foil with a thickness of 5 μm to 15 μm and a Cu foil with a thickness of 5 μm to 15 μm in the X-ray optical path in the order of Zn foil-Cu foil with respect to the X-ray emission direction. The second filter 11 is configured to attenuate the characteristic X-ray fluorescence of Ti by Al foil by arranging a Ti foil with a thickness of 3 μm to 5 μm and an Al foil with a thickness of 20 μm to 400 μm in the X-ray optical path in the order of Ti foil-Al foil with respect to the X-ray emission direction. The filters are configured to satisfy the following equation (5) in the range of irradiated X-ray energy from 10 to 30 keV.

number

[0015] [6] The X-ray spectrometer [1] of the present disclosure may further include a stray X-ray shielding member 12 that shields background light entering the irradiation area. [7] In the X-ray spectrometer [6] of the present disclosure, the stray X-ray shielding member 12 is made of aluminum and preferably has a thickness of 3 mm or more. [8] In the X-ray spectrometers [1] to [7] of the present disclosure, the X-ray source tube 1 may have at least one of W (tungsten), Mo (molybdenum), Rh (rhodium), Cu (copper), Fe (iron), and Cr (chromium) as an anode target. [9] In the X-ray spectrometers [1] to [8] of the present disclosure, the spectroscopic crystal 7 may have at least one of Si(111), Ge(220), Ge(400), and highly oriented pyrolysis graphite (HOPG).

[0016]

[10] The X-ray spectrometers [1] to [9] of the present disclosure may further include a spectrometer adjustment mechanism M configured to irradiate a predetermined irradiation area on the surface of a sample with the spectrally or monochromatically altered X-rays.

[11] In the X-ray spectrometer

[10] of the present disclosure, the spectroscopic crystal 7 is single, and the spectrometer adjustment mechanism M may include a spectroscopic crystal translation stage 6 on which the spectroscopic crystal 7 is placed, and a main rotating table 4 for moving the spectroscopic crystal to a position where the spectrally or monochromatically altered X-rays are irradiated onto a predetermined irradiation area on the surface of the sample.

[12] In the X-ray spectrometer

[10] of the present disclosure, there are multiple spectroscopic crystals 7, and the spectrometer adjustment mechanism M may include a spectroscopic crystal translation stage 6 on which the multiple spectroscopic crystals 7 are placed, a spectroscopic crystal changer 5 that spectrally or monochromatically converts the continuous X-rays using a spectroscopic crystal selected from the multiple spectroscopic crystals 7, and a main rotating table 4 connected to the spectroscopic crystal translation stage 6 and configured to move to a position where the spectrally or monochromatically converted X-rays using the selected spectroscopic crystal are irradiated onto a predetermined irradiation area on the surface of the sample.

[13] In the X-ray spectrometers [1] to

[12] of the present disclosure, the X-ray spectrometer may be at least one of an X-ray absorption spectrometer or an X-ray fluorescence spectrometer.

[0017] [Details of the embodiments of this disclosure] The embodiments of this disclosure will be described in detail below with reference to the drawings. Figure 1 is a top view of the main unit of the X-ray absorption / fluorescence spectrometer. Figure 2 is a system diagram of the X-ray absorption / fluorescence spectrometer. Figure 3 is a diagram illustrating the scattered light and scattered electrons in the X-ray absorption / fluorescence spectrometer shown in Figure 2. The X-ray absorption / fluorescence spectrometer P of this disclosure, described sequentially along the path of the emitted X-rays 8, consists of an X-ray source tube 1, an X-ray source tube translation stage 2, an upstream bellows tube 3, a main rotating table 4, a spectroscopic crystal changer 5, a spectroscopic crystal translation stage 6, a cylindrical curved Johansson spectroscopic crystal 7, a downstream bellows tube 9, a first filter 10, a second filter 11, a shield 12, a silicon drift detector (SDD) 13, and a two-dimensional Si detector 14. Furthermore, the X-ray absorption / fluorescence spectrometer P has a signal processing system that includes a power controller 16, an SDD signal converter (A) 17, a two-dimensional Si signal converter (B) 18, a drive control device 19, and a computing device 20. Furthermore, the X-ray absorption / fluorescence spectrometer P has a base plate 15 and a device housing Q as mechanical components. The main rotary table 4, spectroscopic crystal changer 5, and spectroscopic crystal translation stage 6 constitute the spectrometer adjustment mechanism M.

[0018] X-ray source tube 1 is a water-cooled X-ray source that generates X-rays in the 10 keV to 30 keV range. It uses tungsten, molybdenum, rhodium, etc. as anode targets. For irradiation X-ray calibration, it also incorporates copper, iron, chromium, etc., and has a mechanism that allows each to be changed. The X-ray source tube translation stage 2 operates so that the X-ray output port is always on the Rowland circle, through the linear motion of the X-ray source tube 1 (adjustment of the distance to the spectroscopic crystal 7) and rotational movement in the horizontal (XY) plane by the lower main rotating table 4. Here, the Rowland circle R is a circle whose diameter is the radius of curvature of the cylindrically curved Johansson spectroscopic crystal, or, in other words, a circle on which the X-ray output point, the center of the spectroscopic crystal, and the focal point always move with a constant radius.

[0019] The upstream bellows tube 3 expands and contracts with the linear movement of the X-ray source tube 1. Both ends are sealed with a polyimide film such as Kapton (registered trademark), and by replacing it with helium or the like, the loss of X-rays in the optical path due to the atmosphere is reduced. The main rotary table 4 consists of two tables, one above the other, sharing the same axis of rotation. One is connected to the X-ray source tube translation stage 2, and the other is connected to the spectroscopic crystal translation stage 6. The main rotary table 4 rotates the X-ray source tube translation stage 2 and the spectroscopic crystal translation stage 6, on which the spectroscopic crystal changer 5 is mounted, by a specified angle. The spectroscopic crystal changer 5 has multiple spectroscopic crystals arranged in it and rotates / translates so that the specified spectroscopic crystal is in a predetermined position. The window is sealed with a polyimide film such as Kapton (registered trademark), and by replacing it with helium or the like, the loss of X-rays in the optical path due to the atmosphere is reduced. A spectroscopic crystal changer 5 is mounted on the spectroscopic crystal translation stage 6. The upper main rotating table 4 rotates the cylindrical curved Johansson spectroscopic crystal 7 in the horizontal (XY) plane so that its curved surface lies on the Rowland circle. The cylindrical curved Johansson spectroscopic crystal 7 is an optical element made of Si(111), Ge(220), Ge(400), highly oriented pyrolytic graphite (HOPG), etc., which disperses (spectroscopy) continuous X-rays from the X-ray source tube 1 and focuses them onto the Rowland circle.

[0020] The irradiated X-rays 8 are emitted from the X-ray source tube 1, dispersed and focused by the spectroscopic crystal 7, and then irradiated towards the sample position. The downstream bellows tube 9 is sealed at both ends with a polyimide film, such as Kapton (registered trademark), and by replacing it with helium or the like, X-ray loss in the optical path is reduced. A first filter 10 is attached to the upstream side of the optical path of the downstream bellows tube 9, and / or a second filter 11 is attached to the downstream side. The first filter 10 is composed of Zn foil and Cu foil with a thickness of approximately 5 μm to 15 μm. The first filter 10 reduces background light in the optical path. The second filter 11 is composed of Ti foil with a thickness of 3 μm to 5 μm and Al foil with a thickness of 20 μm to 400 μm. The second filter 11 reduces background light in the optical path.

[0021] Shield 12 is made of aluminum material with a thickness of 3 mm or more and covers the area around the sample. Shield 12 suppresses scattered light and scattered electrons coming from outside the optical path from entering the sample area. The silicon-drift detector (SDD) 13 measures the energy and photon count of fluorescence from the sample or background light generated around the sample location through a shield window (gap) in the energy range of 2 keV to 22 keV. For example, a product from Hitachi-High-Tech Science America, Inc. (Vortex®-60EX) is suitable. The two-dimensional Si detector 14 is a photon-counting two-dimensional detector with detection sensitivity in the X-ray region. For example, a product such as DECTRIS® EIGER2 R 500K (DECTRIS Ltd.) can be used.

[0022] The base plate 15 holds equipment and components such as the main rotary table 4, the two-dimensional Si detector 14, the sample S, and the bellows tubes 3 and 9. It is desirable that it be made of a rigid material with a low coefficient of thermal expansion, such as granite. Preferably, the base plate 15 is placed on a vibration isolation table. The power control device 16 sets the high voltage and current supplied to the X-ray source tube 1 to the specified values. At the same time, it monitors the status. The SDD signal converter (A) 17 performs AD conversion on the signal from the silicon drift detector (SDD) 13 and sends the energy and count of the detected photons to the computing unit 20 after pulse height analysis. The two-dimensional Si signal converter (B) 18 performs AD conversion on the signals from each pixel in the two-dimensional Si detector 14 and sends the number of photons from each pixel, accumulated over a specified time, to the arithmetic unit 20. The drive control device 19 sends the position (angle) of the main rotary table 4, the position of the X-ray source tube 1, the position of the spectroscopic crystal 7, etc., to the reading and calculation device, and moves them to the position specified by the calculation device 20. The computing unit 20 is a computer that controls each device, acquires and stores data from detectors, and has a graphical user interface (GUI) for input and output.

[0023] In Figures 1 to 3, the X-ray absorption / fluorescence spectrometer P refers to the entire measurement unit. The device housing Q is a metal enclosure that covers the entire X-ray absorption spectrometer, preventing X-rays from leaking to the outside and maintaining a constant temperature inside the case. Sample S is the object to be measured, and examples include lithium-ion battery cell cathode materials such as pure metals, oxides, LCO (lithium cobalt oxide), NMC (lithium nickel manganese cobalt oxide), LFP (lithium iron phosphate), and LRO (lithium ruthenium oxide).

[0024] The operation of the device configured in this way will be explained next. Figure 4 is a flowchart illustrating the absorption spectrum measurement process. First, the object to be measured and the corresponding filter are set in the X-ray absorption spectrometer (S100). Next, the rotary table is rotated to the spectral crystal angle corresponding to the target X-ray energy (S102). The spectrally separated X-rays are directed towards the object to be measured (S104). The X-ray signal intensity is acquired from the two-dimensional Si detector 14 (S106). The computing unit 20 determines whether the measurement of the required X-ray energy has been completed (S108). If NO, it returns to S102 and rotates the rotary table to the spectral crystal angle corresponding to the next target X-ray energy. If the answer is YES, the object to be measured is removed from the X-ray absorption spectrometer (S110). Next, with the object to be measured removed, the X-ray signal intensity corresponding to the target X-ray energy is acquired (S112). The calculation unit 20 calculates the absorption spectrum from the obtained measurement data (S114). Then, the calculation unit 20 displays and saves the data (S116). The calculation unit 20 determines whether the measurement of the required object has been completed (S118). If NO, it returns to S100 and sets the filter corresponding to the next object to be measured. If YES, the measurement is complete.

[0025] Next, we will explain the relationship between the object being measured and the corresponding filter. Table 1 is a table illustrating examples of X-ray sources, spectroscopic crystals, first filters, optical path gases, and second filters for sample S being Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Nb, Mo, Ru, Pt, and Au. The anode target of the X-ray source is molybdenum or tungsten, and the applied voltage is selected in the range of 10kV to 25kV. The spectroscopic crystals selected are Si(111), Ge(220), Ge(400), Ge(800), and Si(333). For Zr, Nb, Mo, and Ru, the first filter uses 10μm thick Zn foil and 10μm thick Cu foil. The path gas is helium for Ti, V, and Cr, but air for other samples S. For Fe, the second filter uses 20μm thick Al foil; for Co, Ni, Cu, and Zn, it uses 3μm thick Ti foil and 40μm thick Al foil. For Zr, Nb, Mo, and Ru, it uses 3μm thick Ti foil and 320μm thick Al foil. For Pt and Au, a 3μm thick Ti foil and a 240μm thick Al foil are used.

[0026] [Table 1]

[0027] Here, the densities of Al, Ti, Cu, and Zn (g / cm³) 3 ), mass attenuation coefficient (cm 2 Table 2 shows the numerical ranges for exp(-μρt) used in equations (1) and (2), as well as the values ​​for / g). For metallic elements other than Al, Ti, Cu, and Zn, data can be obtained from sources such as the Isotope Handbook (Japan Isotope Association, 2020) or the NIST (USA) database (https: / / physics.nist.gov / PhysRefData / XrayMassCoef / tab3.html). [Table 2]

[0028] Figure 5 shows an example of background noise when the shield is applied. Density is 2.699 g / cm³ 3 The mass decay coefficient of aluminum for 20 keV photons is 3.442 cm². 2 Since the value is / g, the value at which equation (1) becomes 0.1, i.e., the 1 / 10 value, can be calculated to be 2.47 mm. An aluminum plate with a thickness of 6 mm, which is more than twice this value, was placed around the sample position as shield 12. Figure 5 shows a comparison of the background photon energy spectra with and without shielding, measured by a silicon drift detector (SDD) 13 under the following conditions: X-ray source target: W, spectroscopic crystal: Ge(800), irradiation photon energy: 20 keV. In the spectrum with shielding 12 (solid line), the background intensity due to Cr, Fe, and Cu is reduced to less than half compared to the spectrum without shielding 12 (dotted line). The small peak observed on the lower energy side (18.5 keV) of the 20 keV peak is due to Compton scattering.

[0029] Figure 6 shows an example of background noise when the filter is applied. The effect of the Zn filter alone is that the reduction in Ge background noise is approximately 1 / 10. The first filter 10 was attached to the upstream side of the downstream bellows tube 9, closer to the spectroscopic crystal 7. The second filter 11 was attached to the downstream side of the downstream bellows tube 9, closer to the shield 12 (see Figure 1). Figure 6 shows an example of the background photon energy spectrum detected by SDD13 when each filter was used with the shield in place. In the unfiltered spectrum (dotted line), the Ge Kα fluorescence line of the spectroscopic crystal material is strongly visible. To reduce this Ge fluorescence background, a 10 μm thick Zn foil was used as a filter. As a result, the Ge peak was reduced to about one-tenth without significantly reducing the intensity of the 20 keV irradiation light (dash-dotted line). To suppress the background noise corresponding to Cr, Fe, and Cu, a 10 μm thick Cu foil and a 3 μm thick Ti foil were added as the first filter 10 and the second filter 11, respectively. As a result, the background noise for Ar, Fe, and Ge was further reduced (see solid line in Figure 6).

[0030] Figure 7 shows an example of background noise when the filter is applied. The effect of the Zn+Cu filter is that the reduction rate of Ge background noise is approximately 1 / 100. The first filter 10 was attached to the upstream side of the downstream bellows tube 9, closer to the spectroscopic crystal 7. The second filter 11 was attached to the downstream side of the downstream bellows tube 9, closer to the shield 12 (see Figure 1). Figure 7 shows an example of the background photon energy spectrum detected by SDD13 when each filter was used with the shield in place. In the unfiltered spectrum (dotted line), the Ge Kα fluorescence line of the spectroscopic crystal material is strongly visible. To reduce this Ge fluorescence background, a pair of 10 μm thick Zn foil and 10 μm thick Cu foil was used as a filter. As a result, the Ge peak was reduced to about 1 / 100th without significantly reducing the intensity of the 20 keV irradiation light (dash-dotted line). To suppress the background noise corresponding to Cr, Fe, and Cu, a combination of 3μm thick Ti foil and 320μm thick Al foil was added as a second filter, resulting in a further reduction of Ar, Fe, and Ge background noise (see solid line in Figure 7).

[0031] Figure 8 shows an example of filter (+shield) application, illustrating the X-ray absorption fine structure (XAFS) measurement results using Cu foil as a sample. Figure 8(A) shows the normalized XAFS spectrum, Figure 8(B) shows the normalized X-ray absorption near-end structure (XANES) spectrum, Figure 8(C) shows the XAFS vibration spectrum, and Figure 8(D) shows the Fourier transform spectrum of the XAFS vibration. For the spectra in Figures 8(A) to (D), the dashed lines represent results obtained in the laboratory (without filter), the solid lines represent results obtained in the laboratory (with filter), and the dashed lines represent results obtained using synchrotron radiation. In particular, in Figure 8(C) XAFS vibrational spectrum and Figure 8(D) Fourier transform spectrum of XAFS vibration, the filtered result (solid line) is in very good agreement with the result obtained with synchrotron radiation (dashed line) compared with the unfiltered result (dotted line). This result indicates that the background light on the optical path was successfully suppressed by this disclosure.

[0032] Figure 9 shows an example of shielding (+filter) application, and displays the X-ray absorption fine structure (XAFS) measurement results using Ru foil as a sample. Figure 9(A) shows the normalized XAFS spectrum, Figure 9(B) shows a magnified view of the vicinity of the absorption edge of the normalized X-ray absorption near-edge structure (XANES) spectrum, Figure 9(C) shows the XAFS vibration spectrum, and Figure 9(D) shows the Fourier transform spectrum of the XAFS vibration. For the spectra in Figures 9(A) to (D), the dashed lines represent results obtained using a laboratory setup (unshielded), the solid lines represent results obtained using a laboratory setup (shielded), and the dashed lines represent results obtained using synchrotron radiation. The amplitudes of the XANES spectrum in Figure 9(B) and the XAFS oscillation spectrum in Figure 9(C) are slightly attenuated compared to the results obtained with synchrotron radiation. As shown in Figure 6, the background from Ge and the X-ray source target is significantly suppressed by the filter and shield at around 20 keV of irradiation light. In the XAFS measurements, Figure 9(B) shows the normalized XANES, Figure 9(C) shows the XAFS oscillations, and Figure 9(D) shows the Fourier transform spectrum. The case with shielding (solid line) is closer to the result obtained with synchrotron radiation (dashed line) than the case without shielding (dotted line). This indicates that the background is effectively suppressed by the shielding.

[0033] In the above embodiment, a structure was shown that simultaneously performs laboratory-type X-ray absorption spectroscopy (2D Si detector) and laboratory-type X-ray fluorescence spectroscopy (silicon drift detector) as an X-ray spectrometer. However, this disclosure is not limited to this, and either one or the other may be performed. Furthermore, the technical concept of the X-ray spectrometer of this disclosure, which involves providing stray X-ray shielding members, a first filter, and a second filter to shield against stray X-rays—which include fluorescence scattering from the X-ray source, fluorescence scattering from the spectroscopic crystal, and scattered light from the components (mainly SUS) constituting the X-ray-using device and the surrounding atmosphere—can be applied to all laboratory-type X-ray-using devices, such as X-ray diffraction (XRD) and X-ray reflectivity measurement (XRR), thereby achieving a high effect in reducing background noise.

[0034] Furthermore, in the above embodiments, an embodiment having a spectrometer adjustment mechanism M is shown as a laboratory-type X-ray spectrometer suitable for applications where the type of anode target can be selected as the X-ray source tube, or where the type of spectroscopic crystal can be selected. However, this disclosure is not limited thereto, and in applications where it is desirable to fix the type of anode target and the type of spectroscopic crystal, such as when used as an inspection device for mass-producing a single product in a factory production line, a part of the spectrometer adjustment mechanism M may be omitted. [Industrial applicability]

[0035] The X-ray spectroscopy analyzer described herein provides a laboratory-type X-ray absorption spectroscopy analyzer and / or X-ray fluorescence spectroscopy analyzer that achieves a signal-to-noise ratio (SNR) comparable to that of a synchrotron X-ray source, thus offering significant industrial applicability. [Explanation of Symbols]

[0036] 1...X-ray source tube 2…X-ray source tube translation stage 3…Upstream bellows tube 4…Main Rotary Table 5…Spectroscopic crystal changer 6…Spectroscopic crystal translation stage 7…Cylindrical curved Johansson spectroscopic crystal 8…Irradiation X-ray 9… Downstream bellows tube 10…First filter 11…Second filter 12…Shield (stray X-ray shielding material) 13…Silicon drift detector (SDD) 14…2D Si detector 15… Surface plate 16…Power controller 17…SDD signal converter (A) 18…2D Si signal converter (B) 19… Drive control device 20...Arithmetic device M...Spectrometer adjustment mechanism (4, 5, 6) P...X-ray absorption / fluorescence spectrometer Q...Device enclosure R...Roland Yen S... Sample

Claims

1. An X-ray source tube that generates continuous X-rays, A spectroscopic crystal that spectrally or monochromatically converts the continuous X-rays, At least one of the following: a two-dimensional Si detector that detects X-rays that have passed through a predetermined irradiation area on the surface of a sample, after irradiating the sample surface with X-rays spectrally or monochromatically treated X-rays using the aforementioned spectroscopic crystal, or a silicon drift detector that detects fluorescent X-rays scattered in the irradiation area; A filter provided between the two-dimensional Si detector and / or silicon drift detector and the spectroscopic crystal, including the irradiation region, Equipped with, When the metal element constituting the filter is a single element, it consists of a metal, metal oxide, or alloy that satisfies the following formula (1) in the range of 10 to 30 keV of irradiated X-ray energy. If the metal elements constituting the filter are multiple (i = 1, 2, ..., n: n is a natural number of 2 or more), then the filter shall consist of a metal, metal oxide, or alloy that satisfies the following formula (2) in the range of 10 to 30 keV of the irradiated X-ray energy. X-ray spectrometer. 0.8≦exp(-μρt)≦2.0…(1) In equation (1), μ is the mass attenuation coefficient (cm) at a specific energy when the metal element constituting the filter is a single element. ２ ( / g), ρ is the density of the metal element constituting the filter (g / cm³). ３ ), t represents the thickness of the filter (cm). [Math 1] In formula (2), μ ｉ The mass attenuation coefficient (cm) of the metal element i constituting the filter at a specific energy is the mass attenuation coefficient (cm) ２ / g), ρ ｉ The density (g / cm³) of the metal element i constituting the filter is the density of the element i. ３ ), t ｉ represents the thickness (cm) of the metal element i that constitutes the filter.

2. The aforementioned filter consists of a Zn foil with a thickness of 5 μm to 15 μm and a Cu foil with a thickness of 5 μm to 15 μm, arranged in the X-ray path in the order of Zn foil - Cu foil, with respect to the X-ray emission direction. The X-ray spectrometer according to claim 1, wherein the filter satisfies the following formula (3) in the range of 10 to 30 keV for the energy of the irradiated X-rays. 0.5≦exp(-μ Ｚｎ r Ｚｎ t Ｚｎ -m Ｃｕ r Ｃｕ t Ｃｕ )≦1.5 …(3) In formula (3), μ Ｚｎ , μ Ｃｕ The mass attenuation coefficient (cm) of Zn and Cu, which constitute the filter, at a specific energy. ２ / g), ρ Ｚｎ ρ Ｃｕ The density (g / cm³) of Zn and Cu that constitute the filter is the density of the Zn and Cu that make up the filter. ３ ), t Ｚｎ t Ｃｕ The values ​​represent the thickness (cm) of the Zn and Cu in the aforementioned filter.

3. The aforementioned filter consists of a Ti foil with a thickness of 3 μm to 5 μm and an Al foil with a thickness of 20 μm to 400 μm, arranged in the X-ray path in the order of Ti foil - Al foil, based on the X-ray emission direction. The X-ray spectrometer according to claim 1, wherein the filter satisfies the following formula (4) in the range of 10 to 30 keV for the energy of the irradiated X-rays. 0.5≦exp(-μ Ｔｉ r Ｔｉ t Ｔｉ -m Ａｌ r Ａｌ t Ａｌ )≦1.5 …(4) In formula (2), μ Ｔｉ , μ Ａｌ The mass attenuation coefficient (cm) of Ti and Al, which constitute the filter, at specific energies. ２ / g), ρ Ｔｉ ρ Ａｌ The density (g / cm³) of Ti and Al that constitute the filter is the density of the Ti and Al that make up the filter. ３ ), t Ｔｉ t Ａｌ This represents the thickness (cm) of the Ti and Al in the aforementioned filter.

4. The filter comprises a first filter and a second filter positioned downstream of the spectroscopic crystal. The first filter is made by arranging a Zn foil with a thickness of 5 μm to 15 μm and a Cu foil with a thickness of 5 μm to 15 μm in the X-ray path in the order of Zn foil - Cu foil, with respect to the X-ray emission direction. The second filter is constructed by arranging a Ti foil with a thickness of 3 μm to 5 μm and an Al foil with a thickness of 20 μm to 400 μm in the X-ray path in the order of Ti foil - Al foil, with respect to the X-ray emission direction. The X-ray spectrometer according to claim 1, wherein the filter satisfies the following formula (5) in the range of 10 to 30 keV for the energy of the irradiated X-rays. [Math 2] In formula (5), μ Ｚｎ , μ Ｃｕ , μ Ｔｉ , μ Ａｌ The mass attenuation coefficient (cm) of the Zn, Cu, Ti, and Al components of the filter at specific energies is the mass attenuation coefficient (cm) ２ / g), ρ Ｚｎ ρ Ｃｕ ρ Ｔｉ ρ Ａｌ The density (g / cm³) of the Zn, Cu, Ti, and Al components that make up the filter is the density of the Zn, Cu, Ti, and Al components that make up the filter. ３ ), t Ｚｎ t Ｃｕ t Ｔｉ t Ａｌ The values ​​represent the thickness (cm) of the Zn, Cu, Ti, and Al components of the aforementioned filter.

5. Furthermore, it has a downstream bellows tube provided between the spectroscopic crystal and a predetermined irradiation area on the sample surface, The first filter is provided on the entrance side of the region enclosed by the downstream bellows tube where the X-ray path is surrounded. The second filter is provided on the exit side of the region where the X-ray path is enclosed by the downstream bellows tube. The X-ray spectrometer according to claim 4.

6. Furthermore, the X-ray spectroscopic analyzer according to claim 1, further comprising a stray X-ray shielding member that shields background light entering the irradiation area.

7. The X-ray spectroscopic analyzer according to claim 6, wherein the stray X-ray shielding member is made of aluminum and has a thickness of 3 mm or more.

8. The X-ray spectroscopic analyzer according to any one of claims 1 to 7, wherein the X-ray source tube has at least one of W (tungsten), Mo (molybdenum), Rh (rhodium), Cu (copper), Fe (iron), and Cr (chromium) as an anode target.

9. The X-ray spectroscopic analyzer according to any one of claims 1 to 8, wherein the spectroscopic crystal is at least one of Si(111), Ge(220), Ge(400), and highly oriented pyrolysis graphite (HOPG).

10. Furthermore, the X-ray spectroscopic analyzer according to claim 1 to 9, further comprising a spectrometer adjustment mechanism configured to irradiate the irradiation area on the sample surface with the spectrally or monochromatically altered X-rays.

11. The aforementioned spectroscopic crystal is single, The aforementioned spectrometer adjustment mechanism is, A spectroscopic crystal translation stage on which the spectroscopic crystal is placed, A main rotating table moves the spectroscopic crystal to a position where the spectrally or monochromatically altered X-rays are irradiated onto the irradiation area on the sample surface, An X-ray spectrometer according to claim 10, having the following features.

12. The aforementioned spectroscopic crystals are multiple, The aforementioned spectrometer adjustment mechanism is, A spectroscopic crystal translation stage on which multiple spectroscopic crystals are placed, A spectroscopic crystal changer that spectrally or monochromatically converts the continuous X-rays using a spectroscopic crystal selected from the plurality of spectroscopic crystals, A main rotating table is connected to the spectroscopic crystal translation stage and is configured to move to a position where the spectroscopic crystal selected by the spectroscopic crystal changer irradiates the irradiation area on the sample surface with the spectrally or monochromatically altered X-rays. An X-ray spectrometer according to claim 10, having the following features.

13. The X-ray spectroscopic analyzer according to any one of claims 1 to 9, wherein the X-ray spectroscopic analyzer is at least one of an X-ray absorption spectrometer or an X-ray fluorescence spectrometer.

Images