JPS5942026A - Method and device for separating rare sulfur isotope - 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] This invention separates rare sulfur isotopes by using two infrared lasers to cause gaseous sulfur hexatide to undergo dissociation unique to each isotope. It relates to a method and an apparatus for carrying out the method.

The 5-33 isotope is required to mark organic molecular groups during biological and medical research.

The 5-36 isotope is used in nuclear physics experiments due to its high neutron excess.

Kowara isotope is 0.76% and 00% in natural sulfur.
Since it only contains 15%, separation by conventional methods is extremely expensive.

The wavelength λ of sulfur hexa7ide (SF6) is 10 Bm.
When irradiated with moderately intense external radiation, the gas releases fluorine atoms to form the stable compound sulfur fluoride (SF4). When this reaction occurs at low pressure and with short, intense eraser light pulses, this Ill. It acts to preferentially separate one isotope.

Isotopically pure quantifiable quantities of 5-32 have already been produced by this method. (Reference W, Fu s s.

W, E, Schmid” Berichte der
Bunsen-gessllschaft 83
, 1979, p. 1184), at which time 001 was used for irradiation.
An atmospheric CO2 laser (1°EA laser) emitting a P(20) line with a -100 transition was used. This spectral line overlaps the absorption band of the v3 vibration of the 32 sp 6 molecule.

When the emission spectrum line of the laser overlaps the corresponding absorption band of the 33s26 molecule, it is thought that in principle the 5-33 isotope can be separated in the same manner.

However, experiments have shown that in this case not only the desired isotope but also the most frequent isotope 5-32 is separated.

(Reference 11aronov, Veliknov.

Kolomi 1shii, Lctokl+ov
, N1zlor, ]”is+nennyi,
Ryabov, “Sov, J+Quant+El
, 9f5), May 1979, p. 621). Therefore, if the desired isotopic purity is to be obtained by this method, the separation process must be repeated many times.

Osmium tetroxide (OSO4) exhibits a slight isotopic shift.
) In the case of molecules, an improvement in isotopic selectivity is achieved by using two infrared lasers with different wavelengths for dissociation (Reference A, mb a r t s u+ny a n).

Furzikov, 0orokov, Leto
khov, Maharov, Puretskij,
``Opt. Lett.
Not much improvement compared to the method using O□TEA laser (Ref. Bargatashvi Ii,
Kolomiskij, 11. yal)ov.

5 tarodubtscv ”Sov, J, Quan
t, El, 10(5+”, May 1980, p. 628).

In addition to insufficient selectivity for the 5-36 isotope, 36SF6
There is an additional difficulty that the absorption band of the molecule lies outside the emission wavelength range of the CO2 laser.

Finally, the low concentration of the target isotope is also a drawback. Therefore, the laser beam for dissociation has 5 to] OJ /
A fluence of cA is required, and only focused laser light can meet this at a reasonable cost. In this case, the interaction region is short and limited. Furthermore, if the concentration of the target isotope is low and the pressure required for the separation process is low, only a small amount of laser light will be absorbed. Therefore, in order to effectively utilize laser photons, an intersection area of several hundred meters in length is required.

Due to the problems mentioned above, it is not possible to apply the method adopted for 5-32 to the separation of rare sulfur isotopes.

The object of the invention is to achieve high selectivity when separating gaseous sulfur hexafluoride isotope mixtures by means of laser light.

In order to achieve this objective, the present invention is disclosed in claim 1.
We propose the method listed as a feature in Section 2.

Various embodiments of the method according to the invention and the structure of the apparatus for carrying out the method are set out in the following claims.

This invention makes it possible to obtain rare sulfur isotopes required in the fields of medicine and nuclear physics at an economically reasonable cost.

The details of this invention will be clarified with reference to the drawings below.

FIG. 1 shows an outline of an apparatus for carrying out the method of the present invention.

High pressure CO2 laser 1 and atmospheric pressure CO2 laser 2 (CO
□'l''EA laser) light is collected on the same straight line by a prism 3 and focused through a lens 4 into the reaction area of a flow-through tank 5 which is a reaction cell.The light is removed by using a window 23 on the end face. It enters the flow through tank 5 and passes through the hole 24 in the peripheral edge of the spherical mirror 6.

After being focused, the diverging light is reflected by a spherical mirror 7 placed near the opposite end face of the flow-through tank 5 toward the spherical mirror 6, and is further focused within the reaction area between the two reflecting mirrors. This new focus can be created by appropriately choosing the parameters of the 0-reflector surface, which is spatially separated from the initial focus, and by adjusting the reflector position accordingly. Force tucking can be repeated many times. Using a copper reflector, we were able to realize a 50-fold focus lens without significant reflection loss. In this experiment, the volume ratio to once-through tank 5 was 5:147)
Mixed gas of S1i"6 and II2 at 01 to 0.2mba
The sample was charged at a pressure of r and treated at a temperature of 1.50 K.

The emission wavelength of high pressure CO2 laser-1 is 91 to 108/l
It can be adjusted continuously within the range of tn. 5-
For the separation of 33 isotopes, the wavelength λ is adjusted to 10.6441 μm (939.5 cm in wavenumber). This wavelength overlaps with the characteristic Q technique of transition.

The length τ of the laser light pulse is 50 ns and the energy is 50 to ]00 mJ. The electronic control unit 8 causes the 'l'EA laser 2 to be emitted in a manner similar to that of the first laser.
1) with a delay of approximately 2Qns. Laser 2 is 001. It is tuned to a P(30) line with a shift of -100M, and its pulse energy is about 5J. By laser light irradiation, part of the SF6 molecule is dissociated into SF4 and one atom. The F atom reacts with hydrogen to form hydrogen fluoride IIF. SIi'6. H2, SF4
and I(F mixture gas is N a OLl and 1-■20
is compressed through a trap 10 containing a At that time, 5I
The concentrated 33S in N4 is converted into an aqueous solution as sulfite by the following reaction.

SF4+21120→S 02 +41-rF HF contained in the mixed gas also reacts with the alkaline solution,
SF6 and II2 are not linked. These are buffer tank 1
1 and finally returned to the once-through tank 5 through the pressure reducing valve 12. After a certain operating time, the concentrated SF6 gas is discharged through valves 13 and 14 and fresh gas with natural isotope concentration is added through valve 15.

By excitation with a continuously wavelength-tunable high-pressure laser and a C02TEA laser, it has been shown that much higher selectivity and greater yields can be achieved than with conventional methods. In this case, the intensity of the laser light (W/cnl) is decisive for the first excitation process, and the fluence (J/ctrf) is decisive for the second excitation process. According to the invention, the structural dimensions of the reflector device in the flow-through tank 5 are such that, due to focusing, in the interaction region between the reflectors 6 and 70 an intensity of 2-3 MW/cA and a strength of 3 to 6 J/cA is achieved.
The fluence is chosen such that a fluence of cA is achieved.

The use of multiple forcing mirror devices is a major improvement and provides the following benefits:

The ability to repeat 50 instant force-twisting increases the size of the interaction region and thus the yield per laser pulse by a factor approximately equal to the number of force-twisting repetitions compared to the case of tun-force twisting. be able to. Since the total isotope separation cost is primarily due to the cost of photon generation, the separation cost decreases correspondingly to the above increase.

A high reflectance of the mirror surface is a prerequisite for the effectiveness of the multiple reflector device. In the reaction cell, highly reactive T-TF' and SF4 are formed by isotope-selective photodissociation of SF6, so care must be taken to prevent these products from reaching the mirror area as much as possible. For this purpose, the unirradiated mixed gas is introduced into the center between the mirror surfaces of the reaction cell through the hole 20, and the irradiated gas is sucked out through the exhaust hole 21 provided in the center of the interaction area between the mirror surfaces. 1 for mirror surface? The gas flow flowing out from the center between the mirror surfaces is bent toward the periphery by the gas flow guide plate 22 provided while maintaining JjM, so that it flows parallel to the mirror surfaces.

The guide plate 22 is fixed concentrically to the mirrors 6 and 7 as shown in FIG. 2, and its diameter is selected so that the laser reflected light on one circumference is not covered. Since the fluence of the laser light beam in this area is significantly lower than in the interaction region, no reaction products are created.

The above method explained using the separation of 33S as an example is 5-3.
It is also effective for separating 6 isotopes. However, in this case, the absorption band is at the wavelength λ = 10.936 μm (=914.43c
nL-1), which lies outside the emission wavelength range of conventional Co2TEA lasers. By operating this laser with the combination of rare isotopes 13CI8Q□, its emission wavelength can be shifted, but the operating cost becomes enormous and economical 5-36 isotope separation becomes impossible. By stimulated Raman scattering for gaseous deuterium, the wavelength of the laser light can be shifted to the longer wavelength side by an amount corresponding to 179.04 cm-'. According to the present invention, for the separation of 5-36 isotopes, the emitted light of lasers 1 and 2 is shifted to the longer wavelength side by the Raman effect before interacting with S1-6 gas. In this case, the high-pressure CO2 laser-1 has a wavelength of λ1
= 9.1451tm, whereas Co2-
'l' EA laser 2 is n of 001-020 transition, (
38) Tune in to the line. This device allows effective separation of 5-36 even at low initial concentrations.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of an apparatus for implementing the method according to the present invention;
FIG. 2 is a front view and a sectional view of a spherical reflector and a gas flow guide plate placed in front of it. In Fig. 1, 1 and 2: infrared laser, 5: flow-through tank, 6 and 7: spherical reflector. 8118) Agent Patent Attorney Tomimura −

Claims (1)

[Claims] 1) Sulfur hexatide gas cooled to <15 or
irradiation with a first laser beam of a continuously variable wavelength tuned to exhibit sharp resonance in the Q branch region of the ν3 vibration of the isotope to be considered as a monomer, and having an intensity of 2 to 3 M W / crJ in the interaction region. , then the emitted light is 4
Using two infrared lasers, which are shifted to the longer wavelength side by ~6 cm-' and actuated by a second laser beam with a fluence of 3-6 J/l:FJ in the interaction region, the gas A method to separate rare sulfur isotopes by dissociation unique to each isotope of hexafluoride ions. 2) using a continuously tunable high-pressure CO2 laser tuned to a wavelength of 10.649 μm as the first laser;
P(30) of the ooi-100-transition as the second laser
A method according to claim 1 for the separation of 5-33 isotopes, characterized in that a C02TEA laser emitting radiation is used. 3) High voltage C with wavelength λ+=9.145μm as irradiation light source
Using a 02 laser and a C02TEA laser that emits the R(38) line of the 001-020 transition, the emission wavelength of this laser is converted to a range effective for isotope-specific dissociation by Raman scattering in gaseous deuterium. A method according to claim 1 for separating the 5-36 isotope. 4) directing the emitted light of both lasers along the same straight line in one spherical mirror arrangement so that these rays are focused multiple times within the gas volume, thereby producing a high light intensity over one extended section; 2. The method according to claim 1, wherein: 5) Contains two infrared lasers (1, 2) and a flow-through tank (5) as a reaction cell, the infrared lasers are emitted into the flow-through tank, and the emitted light is guided and focused, and the two infrared lasers face each other in the flow-through tank. The spherical mirrors (6, 7) are provided with a hole (20
), the irradiated mixed gas flows through this hole into the interaction area of the mouth flow tank (5), and a suction hole (21) is provided for sucking out the irradiated mixed gas and reaction products. A flow-through tank (5) is installed in the center of the interaction area of both spherical mirror openings.
A device for separating rare sulfur isotopes. 6) A gas flow guide plate (22) is provided in front of the central hole of the mirror (6, 7) and at a certain distance therefrom to direct the mixed gas towards the periphery of the mirror (6, 7). An apparatus according to claim 5, characterized in that: