JPH05501610A - X-ray spectrometer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] X-ray spectrometer The present invention relates to X-ray spectrometers, and in particular to analytical results for use in such spectrometers. It's about crystals.

In X-ray spectroscopy, an X-ray source typically irradiates the sample under examination with X-rays (bo ■bard).

As a result, the sample emits secondary X-rays having wavelength characteristics of the constituent elements of the sample. this Bragg's law for secondary radiation, n, λ=2. d, sin θ Here, n = integer (“order” of diffraction) λ = wavelength d=crystal lattice spacing, and θ = angle of incidence as a diffraction device to separate the beams into separate beams corresponding to different wavelengths. Therefore, a suitable single crystal is used.

The intensity of the emitted radiation at a particular wavelength is then measured using a suitably placed detector. and thereby qualitative and/or quantitative measurements of the corresponding elements are made. .

X-ray spectrometers can be divided into two types: A “sequential” spectrometer that can be used to measure several elements simultaneously and a “simultaneous” spectrometer that can be used to measure several elements simultaneously. “It is a spectrometer.The analysis crystal used in a sequential X-ray spectrometer is usually a flat one. However, those used in simultaneous spectrometers are curved in the vertical direction. Plane For crystals with The drawback is that it tends to be dominated by the vertical divergence allowed by the meter.

In short, this results in an asymmetrical line shape toward higher order 2θ angles.

Transversely curved crystals have also been proposed (see European Patent Application No. 0290058A). ), Matago (recently, curved ones in both vertical and horizontal directions have also been proposed (European Patent No. No. 0339713A, published after priority 8 of the present invention). However, this These curved crystals require heat treatment or the crystal to form the required curved surface. It has the disadvantage that it involves the application of mechanical stress. This means that there are imperfections in the crystal lattice. , resulting in a vertical divergence that at least partially offsets the beneficial effects of the curved surface. come Additionally, the optimal degree of curvature varies depending on the specific element being tested; It is necessary to use a crystal like this or to make some compromise in the radius of curvature. be. Moreover, the crystal must be thin (in order to curve ), problems arise with the use of high-energy X-rays that penetrate relatively deeply into crystals. Let's live.

Therefore, for use in X-ray spectrometers, it differs from ordinary planar crystals in several important respects. It also offers significantly simpler construction and tunability than the curved crystals described above. We have devised a crystal arrangement that provides several advantages.

According to the present invention, an X-ray source for irradiating a sample to be analyzed with X-rays, For analysis to separate secondary radiation emitted by a material into individual wavelengths by diffraction An X-ray spectrometer consisting of a crystal and an X-ray detector. at least two planes arranged so that their cross-sections are shallow U- or ■-shaped; An X-ray spectrometer is provided, characterized in that it is comprised of segments.

The X-ray spectrometer of the present invention is firstly a known X-ray spectrometer including a planar crystal for analysis. It has the advantage of producing a much higher intensity of radiation at the detector. On top of that , the resulting spectral lines can be narrower and more symmetrical, This improves resolution.

Furthermore, this spectrometer has advantages over spectrometers containing laterally curved crystals. The production of crystals for analysis is simpler, and this production involves e.g. heating or This method does not involve processing of crystals that has disadvantageous effects such as polishing. Furthermore, i.e. adapt the tilt angle of the outer segment of the crystal to the specific element under analysis so that it can be easily optimized. In other words, a kind of "tuning" is possible.

A crystal can be composed of any number of segments, e.g. up to 7 segments. Wear. However, increasing the number of segments beyond about 3 will improve the performance of the crystal. Do not improve quality (it will increase costs).

The crystal for analysis has a central segment and a cross section of the crystal outside the plane of this central segment. Two outer segments adjacent to the central segment are angled to have a shallow U-shape. Particularly preferably, it consists of three segments.

"Outer segment" is the central segment when viewed along the incident beam of secondary radiation. means the right and left of

The central segment of the analytical crystal is preferably the main part of the crystal. For example preferred In the specific example, the crystal consists of three segments with widths in the ratio 1:2:1. be done. The crystal is, for example, 16mm wide in the center segment and 8mm wide in the outer segment. The total size can be 60 mg x 32 mm.

The angle of inclination of the outer segments outside the plane of the central segment is generally , for example, about 1 to 2 degrees. As mentioned above, this angle can be adjusted . This adjustment requires that, for example, the mounting placed under the analysis crystal penetrates the plate and Simple mechanical steps such as adjusting the screws that engage the outer segments It can be accomplished in stages.

The special feature is that the crystal segments are fixed to thin metal sheets that act as springs. It was found to be convenient for This spring is installed in the area of the central segment. The attachment is glued to the plate and the adjusting screw is spring-loaded in the area of the outer segment. engage against. The material and thickness of this metal spring are If it has a gender, it is not definitive. For example, the spring is o, 15cm thick. It may be steel.

The crystals may be of any suitable material, including those commonly used for this purpose. You can. Such materials include clinochlore, fluorophore, etc. Potassium hydrogen talate, rubidium hydrogen phthalate, muscovite, ceracola, dihydrogen phosphate ammonium, ethylenediamine D-tartrate, pentaerythritol, α-quartz, graphite, germanium, silicon, sodium chloride, fluoride thium, topaz, indium antimonide and thallium hydrogen phthalate, etc. is included.

The thickness of the crystal segments is not critical, but is typically up to about 5 mm, typical Generally speaking, it is about 1■ or 21.

The crystal segment does not necessarily have to consist of a single crystal plate; It may consist of a carrier coated with a material that reflects radiation. child Examples of materials such as lead mellisate, lead lignocerate, lead stearate and lead laurate.

Elements that can be measured using the X-ray spectrometer of the present invention include For example, Al5Si, PSS, These include light elements such as CI and Mg and heavy elements such as rare earths.

Apart from the analysis crystal, the remaining parts of this X-ray spectrometer are of standard specification. and is well known to those skilled in the art.

Particularly preferred embodiments of the invention will now be described with reference to the accompanying drawings, which are intended to be illustrative only. Let me explain.

FIG. 1 is a schematic diagram of an X-ray spectrometer according to the invention; FIG. 2 shows a part of the spectrometer of FIG. It is a perspective view showing in more detail the arrangement of the constituent sample, analysis crystal, and detector. : FIG. 3 is an oblique view along the incident path of the secondary radiation of the analytical crystal; FIG. 4 is an end view of the crystal mount of FIG. 2 with the crystal in place; and FIG. 5 is a plan view of the installation of FIG. 4.

Referring first to Figure 1, an X-ray spectrometer is constructed using a housing that houses an X-ray tube (2). (1), a sample changer (3) that sends the cassette containing the sample (4) into the device; ), and the detection unit consists of a primary collimator (6) and an analytical crystal (7). and a detector (8) attached to a secondary collimator (9). Ru. The angular movement of the analysis crystal (7) and the detector (8) is a moiré fringe goniometer. (10).

The X-ray tube (2) is of normal specification, for example 0.127mm beryllium. Rhodium-positive with berryliu+* end window Powered by a stabilized 3K1 generator with a polar tube and a maximum voltage of 60kV and maximum current of 100mA. energized.

As can be seen more clearly from Figure 2, the primary collimator (6) and the secondary collimator The motor (9) consists of a set of parallel plates. moire fringe goniome The tar (10) is a fixed radial grid (11) with a scale of 18,000, the crystal (7) and a read head (12, 13) for each of the detectors (8) and the detectors (8); A drive motor that maintains a 2:1 connection movement between the container (8) and the analysis crystal (7) - (not shown). Maintain a 2:1 coupled movement between the detector and the crystal. Of course, you can use a more conventional goniometer that includes a reduction gear to Yes, but software-controlled moiré fringe goniometers are faster. It provides many benefits including being able to move more accurately.

The motors for the detector (8) and analysis crystal (7) are driven through a reduction gear. rather than directly, one DC motor rotates the drive shaft of the analysis crystal. , and one DC motor rotates the drive shaft of the detector. Crystal (7) and detector The angular position of (8) measures each read head fringe.

In various embodiments, the device is equipped with one or more detectors and one or more analytical crystals. You can also prepare. In such cases, the detector and crystal are placed on a rotatable drum. The selection of appropriate detectors and/or crystals This is done by rotating a drum under processor control. Additionally, some independent It is also possible to install a goniometer in one device.

In addition, the device includes other conventional equipment not shown, such as various Examples for analyzing electronic control elements and vacuum pump devices and/or liquids For example, by means of flushing the device with a gas such as helium or dry nitrogen. be. Also, insert a primary beam filter between the X-ray tube (2) and the sample (4). This filter can be made of copper, aluminum or iron, for example. .

Referring to Figure 3, the analysis crystal (7) has a central segment with a size of 16ml 1 x 601cm. (71) and two outer segments (7 It consists of three planar segments: 2, 73). Outer segment (72 , 73) are inclined approximately 16-2° outside the plane of the central segment (71) and Therefore, the transverse cross section of crystal (7) forms a shallow U-shape (the angle is not emphasized in the figure). be). The arrow in FIG. 3 indicates the incident line of secondary radiation.

The inclination of the outer segments (72, 73) is shown more clearly in Figures 4 and 5. The crystal segment is mounted on a thin steel spring (74). This spring is attached to the plate (75) in the area of its central segment (71). It is fixed (with adhesive). Installation is done through a threaded hole in the plate (75). There are four adjustment screws (81), two of which are located on each outer segment (72, 73). located below.

The adjusting screw (81) is fitted with a steel spring in the area of the outer segments (72, 73). is engaged with the lower side of the The angle of inclination of the outer segments (72, 73) is adjusted using the adjustment screw. It can be adjusted by rotating (81).

In use, the X-ray source (2) irradiates the sample (4) with X-rays, and the sample (4) Emit secondary X-rays characteristic of the constituent elements. This secondary radiation beam is The light is focused by a meter (6) and is incident on an analysis crystal (7). Bragg's condition is satisfied, that is, the angle of incidence θ is sin θ=n, λ/2. d When , the secondary radiation is diffracted by the crystal (7).

The secondary collimator (9) and the detector (8) detect the diffracted radiation at wavelengths characteristic of the elements in the sample. Automatic positioning by goniometer (10) to measure the intensity of the radiation be done.

Submission of translation of written amendment (Article 184-8 of the Patent Act) May 28, 1992

Claims (1)

[Claims] 1) X-ray source for irradiating X-rays onto the sample to be irradiated; Analytical crystals and X - An X-ray spectrometer consisting of a ray detector, in which the crystal for analysis has a shallow lateral cross section. - or V-shaped at least two planar segments arranged so as to be in the shape of An X-ray spectrometer comprising: 2) The method according to claim 1, wherein the crystal for analysis consists of 2 to 7 planar segments. X-ray spectrometer. 3) The analysis crystal has a central segment and a section of the crystal outside the plane of this central segment. Two adjacent central segments inclined so that their cross-sections have a shallow U-shape. X- according to claim 1 or 2, consisting of three segments with an outer segment. Line spectrometer. 4) X according to claim 3, wherein the central segment of the analytical crystal is the main part of the crystal. -Line spectrometer. 5) X- as claimed in claim 4, wherein the three segments have widths in the ratio 1:2:1. Line spectrometer. 6) The X-line segment according to claim 3, wherein the angle of inclination of the outer segment is adjustable. Light device. 7) Adjustment of the inclination of the outer segments is possible when the central segment is fixed The X-ray segment according to claim 6, carried out by an adjustment screw extending through the plate. Light device. 8) The planar segment is fixed to a thin metal sheet that acts as a spring. The X-ray spectrometer according to claim 1. 9) Small crystals arranged so that the lateral cross section of the crystal has a shallow U- or V-shape. Analytical for use in X-ray spectrometers, consisting of at least two planar segments crystal.