JP3323670B2 - Radiation spectrometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiation spectroscope for effectively focusing radiation generated from a sample.

[0002]

2. Description of the Related Art For example, in a conventional X-ray fluorescence spectrometer, a sample is irradiated with primary X-rays, and an appropriate X-ray is selected from secondary X-rays generated from the sample in accordance with the wavelength of a specific X-ray fluorescence. A single spectral element having a lattice spacing is installed at an appropriate spectral angle, and the fluorescent X-rays are separated and incident on an X-ray detector.

[0003]

However, in the above-mentioned prior art, in particular, in the case of long-wavelength fluorescent X-rays generated from light elements, the intensity of the fluorescent X-rays incident on the X-ray detector is not sufficient, and Analysis may be difficult.

The present invention has been made in view of the above-mentioned conventional problems. Even if the secondary radiation generated from the sample has a long wavelength, the intensity of the secondary radiation incident on the radiation detector is sufficient. An object of the present invention is to provide a radiation spectrometer capable of performing accurate analysis.

[0005]

In order to achieve the above object, a spectroscope according to claim 1 is arranged in parallel with each other in a path of secondary radiation generated from a sample irradiated with primary radiation generated from a radiation source. A plurality of dispersive elements arranged at different lattice spacings, the dispersive elements being configured to diffract secondary radiation of the same wavelength and to make the diffracted secondary radiation enter a single radiation detector. It is.

[0006]

In the spectrometer according to the first aspect, the secondary radiation of the same wavelength generated from the sample is diffracted by a plurality of spectral elements having different lattice spacings and is incident on a single radiation detector. The intensity of the secondary radiation incident on the radiation detector increases as compared with the case where the light is separated by a single light-splitting element. Thereby, the sensitivity is improved, and accurate analysis can be performed even when the secondary radiation has a long wavelength.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. First, a first embodiment will be described. In FIG. 1, a primary X-ray 2 generated from an X-ray source 1 is applied to a sample 3, and a secondary X-ray generated from the sample 3 is narrowed by a divergence slit 4. Here, the first X-ray spectrometer is used.
The radiation spectroscope 20 of the embodiment is disposed so that the lattice planes 11 and 12 are parallel to each other in the respective passages of the two secondary X-rays 5 and 6 passing through the diverging slit 4.
Next X-rays 5 and 6 are incident at incident angles θ ₁ and θ ₂ , respectively, and curved first and second spectral elements 7 and 8 formed of artificial gratings for dispersing fluorescent X-rays 14 and 15 having specific identical wavelengths.
It has. X-rays other than the fluorescent X-rays 14 and 15 are excluded by the light receiving slit 9, and the fluorescent X-rays 14 and 15 passing through the light receiving slit 9 are converted into a single X-ray detector 10.
Is incident on. As the curved first and second dispersive elements 7, 8, for example, a Johann type, a Johansson type, or a log spiral type can be used.

[0008] Here, the incident angle theta ₂ is made larger than the incident angle theta _1, the phase lattice spacing d ₁ of the different first spectral element 7 and the lattice spacing d ₂ of the second spectral element 8, below There is such a relationship. First, assuming that the wavelengths of the fluorescent X-rays 14 and 15 to be separated are λ from the Bragg condition, 2d ₁ × sin θ ₁ = λ ( ₂ ) 2d ₂ × sin θ ₂ = λ (2) 4 secondary X-rays 5 and 6
, And the incident points of the secondary X-rays 5 and 6 on the spectral elements 7 and 8, that is, the spectral elements 7 and 8
Lattice planes 11 and 12 passing through points A and B at the center of each lower surface
Considering the normal 13 to, from the geometrical relationship, θ ₁ = θ ₂ −φ (3)

From the above relationship, the lattice spacing d ₁ and the incident angle θ ₁ in the first spectral element 7 and the lattice plane d ₂ and the incident angle θ ₂ in the second spectral element 8 are appropriately set as follows. it can. Temporary lattice spacing d ₁
If the first spectral element 7 is adopted, the first spectral element 7
Is the incident angle θ _{1 at} which the fluorescent X-ray 1
It is determined from the wavelength λ of 4 by the following equation (4) obtained by modifying the equation (1). θ ₁ = sin ⁻¹ (λ / 2d ₁ ) (4) When the incident angle θ _{1 on} the first spectral element 7 is determined,
If the angle φ between the two secondary X-rays 5 and 6 that have passed through the diverging slit 4 is determined, the incident angle θ ₂ in the second spectral element 8 is given by the following equation (5) obtained by modifying equation (3). It is determined. θ ₂ = θ ₁ + φ (5) When the incident angle θ ₂ in the second spectral element 8 is determined,
The lattice spacing d ₂ of the second spectral element 8 is determined by the following equation (6) obtained by modifying the equation (2). d ₂ = λ / 2 sin θ ₂ (6)

In the first embodiment, since the curved spectroscopic elements 7 and 8 are used, for example, one secondary X-ray 5 passing through the divergent slit 4 is incident on the lower surface of the first spectroscopic element 7. Irrespective of this, even at the point A at the center of the lower surface, the light is similarly diffracted at the incident angle θ ₁ . That is, in FIG.
For simplicity, one secondary X-ray 5 that has passed through the divergence slit 4 is illustrated as a representative example of the secondary X-ray 5 incident on a point A at the center of the lower surface of the first spectral element 7; 2
This is a secondary X-ray that spreads from the point P ₁ where the secondary X-ray 5 has passed through the divergence slit 4 to the entire lower surface of the first spectral element 7.

As one of the diffracted fluorescent X-rays 14, the fluorescent X-rays 14 incident from the point A at the center of the lower surface of the first spectral element 7 to the incident point Q ₁ to the light receiving slit 9 are shown as a representative example. in fact, the entire lower surface of the first spectral element 7, a fluorescent X-ray focusing the incident point to Q ₁ to the receiving slit 9. This situation is the same for the other secondary X-rays 5 incident on the second spectral element 8 and the diffracted fluorescent X-rays 15.

Next, the operation of the first embodiment will be described. The primary X-rays 2 generated from the X-ray source 1 are irradiated on the sample 3, and the secondary X-rays generated from the sample 3 are narrowed by the divergence slit 4 into two secondary X-rays 5 and 6. The two secondary X-rays 5 and 6 passing through 4 are respectively incident on the first and second spectral elements 7 and 8 of the X-ray spectroscope 20, and
Desired X-rays 14 and 15 of the same wavelength are separated into respective light and passed through the light receiving slit 9 to form a single X-ray detector 10.
Incident on Thereby, the intensity of the fluorescent X-rays incident on the X-ray detector 10 increases.

Here, in the X-ray spectroscope 20, the first spectral element 7 is made large in the left-right direction in FIG.
The secondary X-rays 6 incident on the spectral element 8 are also incident on the first spectral element 7 so that only the first spectral element 7 separates fluorescent X-rays having the same intensity as in the first embodiment. X-ray detector 1
It is also conceivable to make the light incident on zero. However, it is difficult to manufacture such a large curved spectroscopic element, and even if the spectroscopic element can be manufactured, the focal point of the diffracted X-rays incident on the center and the end of the diffracting surface of the spectroscopic element may be reduced. It is unavoidable that the X-ray detector 10 is shifted, and the convergence on the X-ray detector 10 is poor. In contrast,
The present invention does not have such a disadvantage.

In general, the intensity of fluorescent X-rays that are split by the spectroscopic element and incident on the X-ray detector becomes weaker as the optical path of the X-ray is longer and the lattice spacing of the spectroscopic element is smaller. . In the first embodiment, the fluorescent X-rays 15 that are split by the second spectral element 8 and enter the X-ray detector 10 are smaller than the fluorescent X-rays 15 that are split by the first spectral element 7 by the sample 3.
Since the light path from the light source to the X-ray detector 10 has a long optical path and is separated by the second spectral element 8 having a narrow lattice spacing d ₂ , the fluorescent light X incident on the X-ray detector 10 The line intensity decreases.

However, if the fluorescent X-rays 14 and 15 of the same wavelength separated by the first and second spectral elements 7 and 8 are combined and incident on a single X-ray detector 10, a single first spectral An intensity 1.5 times or more that of the case of only the fluorescent X-rays 14 separated by the element 7 is obtained. Thereby, 2 generated from the sample 3
Even if the next X-rays 5 and 6 have long wavelengths, the intensity of the fluorescent X-rays 14 and 15 incident on the X-ray detector 10 is sufficient and accurate analysis is possible.

Next, a second embodiment will be described. First
In the embodiment, the first and second light-splitting elements 7 and 8 are arranged so that their lattice planes 11 and 12 are parallel. However, the present invention is not limited to the lattice planes 11 and 12 being parallel. . For example, in the second embodiment shown in FIG. 2, when there is only one gap Q _{3 in the} light receiving slit 29, the primary X-ray 2
A straight line 5 connecting the point of incidence O on the sample 3 with the gap P ₃ below the divergent slit 24, the gap P ₃ and the light receiving slit 2
The point of intersection D of the line segment 31 connecting the gap Q ₃ with the vertical bisector 23 at the center of the lower surface of the first spectral element 27 is defined as the incident angle θ ₃ of the first spectral element 27. The vertical 2
It is determined by setting perpendicular to the bisector 23.

Similarly, a straight line 6 connecting the point O where the primary X-ray 2 enters the sample 3 and the gap P _{4 above the} diverging slit 24
And the intersection E of the perpendicular bisector 25 of the line segment 32 connecting the gap P ₄ and the gap Q ₃ of the light receiving slit 29 to determine the arrangement of the second spectral element 28 and the incident angle θ _4. Can be Lattice plane distance d between first and second spectral elements 27 and 28
₃ and d ₄ are obtained from the above equation (6). The X-ray spectrometer 30 configured as described above has the same operation as the X-ray spectrometer 20 of the first embodiment.

In addition to the first and second embodiments, FIG.
In the above, the gap of the diverging slit 4 may be only one. The incident points of the primary X-rays 2 on the sample 3 are actually distributed not only at one point O but also on the surface of the sample 3, and the secondary X-rays generated from different incident points are transmitted through the divergence slit 4. By passing through a single gap, a plurality of secondary X-rays 5 and 6 can be respectively incident on a plurality of spectral elements 7 and 8 as in the first embodiment. Also, for example, in FIG. 1, the X-ray fluorescence 14 emitted from a point A at the center of the lower surface of the first spectral element 7
Is incident on the gap Q _{2 above} the light receiving slit 9, and the fluorescent X-rays 15 emitted from the center B on the lower surface of the second spectral element 8 are incident on the gap Q ₁ below the light receiving slit 9. They can also be placed.

In the first embodiment, for example, two curved light-splitting elements 7 and 8 having different lattice spacings d ₁ and d ₂ are used, but the light-splitting element used in the present invention is not limited to a curved light-splitting element. Alternatively, two flat spectral elements having different lattice spacings may be used. In this case, a solar slit is used for the divergence slit 4 and the light receiving slit 9, and the light is made to enter the spectral elements 7, 8 or the X-ray detector 10 in a parallel light state. Further, the number of spectral elements used in the present invention is not limited to two,
A plurality of three or more spectroscopic elements can also be used.

In the first and second embodiments, the radiation to be split is X-rays. However, the radiation that can be split in the present invention is not limited to X-rays, and radiation other than X-rays, such as synchrotron radiation, etc. The present invention can also be used.

[Brief description of the drawings]

FIG. 1 is a side view of a first embodiment of the present invention.

FIG. 2 is a side view of a second embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Radiation source, 2 ... Primary radiation, 3 ... Sample, 5,6 ... Secondary radiation generated from sample 7,8 ... Spectroscopy element, 10 ... Radiation detector, 14, 15 ... Diffraction of the same wavelength 2 Next radiation, 20 ... Radiation spectrometer.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 23/223 G21K 1/06

Claims (1)

(57) [Claims] 1. A plurality of spectroscopic elements arranged in parallel with each other in a path of secondary radiation generated from a sample irradiated with primary radiation generated from a radiation source and having different lattice plane intervals. Is a radiation spectrometer set to diffract secondary radiation of the same wavelength and make it incident on a single radiation detector.