JPS6245327A - Working substance and method of separating laser isotope - Google Patents

Abstract

PURPOSE:To efficiently separate <29>Si and <30>Si, by irradiating a working substance comprising a specific fluoromonosilane compound with infrared laser to separate the isotopes of Si. CONSTITUTION:As a working substance, a fluoromonosilane compound represented by SiFnX4-n (wherein X is H, Cl, Br or I and 1<=n<=3) such as SiF3H or SiF3Br or by SiFnR4-n (wherein R is an alkyl group or a halogen derivative thereof and 1<=n<=3) such as SiF3CH3 or SiF2(CH3)2 is used. This compound is irradiated with carbon dioxide laser, HF laser or laser coming to infrared rays by converting a wavelength to separate isotopes of Si. As a result, <29>Si and <30>Si can be efficiently separated and manufacturing cost is reduced as compared with a mass analytical method and a large amount of isotopes of Si can be inexpensively obtained.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a working material used in laser isotope separation for separating isotopes of Si, and a method for producing Si isotopes using this working material.
Regarding laser isotope separation method.

(Prior Art) The absorption spectrum of a molecule in the infrared region with a wave number of 102 to 103 cm-' corresponds to a change in the vibrational state of the molecule and often shows significant isotopic effects. Therefore, it is possible to focus on a molecule containing a specific isotope, irradiate the molecule with light in the vicinity of a large wave number of absorption, selectively excite -C, induce a chemical reaction, and lead to separation. If a normal molecule absorbs only one photon of light in the above-mentioned region, the energy is insufficient and no chemical reaction occurs. However, when exposed to powerful infrared laser light, the molecules absorb up to several dozen photons and break down. This kind of decomposition is called infrared multiphoton dissociation.

Natural Si has isotopes with masses 28.29 and 30 C
”S i]: [”S i]: [”S i'l
=92, 23:4.67:3.10.

Until now, the isotope separation of Si by infrared multiphoton solution 1 has hardly been studied, and only S + F4
In an experiment using a carbon dioxide laser using as the working material, 2
93iF4 and 3034. (J, L, Lyman and S, D
, Rockwocd; J, 8pp1. Phys.
,, Vol, 47, No. 2, P
, 595-601, (1976)).

However, the selectivity of enrichment according to this experiment is extremely low, and the moisture content of Si and 30S1 only increases by 5 to 6 degrees, making KL intolerable in practical terms.

On the other hand, the present inventors previously discovered that S ia X b f-
f c (2≦a≦3.0≦b≦2a+2.2a+2=b
The polysilane compound represented by +c, X is the same or different halogen atom) is in the infrared laser oscillation region93
The company discovered that it has an absorption in the range 0 to 106106O' that corresponds to the vibration of the molecule, and that when irradiated with pulsed infrared laser light in the vicinity, it causes infrared multiphoton dissociation extremely efficiently and decomposes into lower-order silane, and filed a patent application. I went (Special request 1976)
0-21577).

(Object of the Invention) The object of the present invention is to provide a laser isotope separation method and working material for efficiently separating Si isotopes, which were obtained as a result of intensive research by the present inventors after the application was filed. It is in.

(Structure of the Invention) The present invention uses SIF n X 4-n as a working material.
(X is H, Cl, Br, I, 1≦n≦
3) or 5IFnR4-h (R is an alkyl group or its halogen derivative, where 1≦n≦3) using a fluoromonosilane compound, and by irradiating this fluoromonosilane compound with an infrared laser, the Si isotope is Separated.

The fluoromonosilane compound as a working substance is S + F s HSS IF 3 CIt XS
1F 3 B r, S I F2H2, S I FC
Examples of infrared lasers include carbon dioxide laser, HF laser, and lasers that convert the wavelength to become infrared (e.g., water Raman laser) etc. are included. Among these, carbon dioxide laser is particularly preferred because of its good wavelength matching with molecular vibration and high laser beam intensity.

The fluoromonosilane compound has a strong absorption band in the infrared laser oscillation region that corresponds to the stretching vibration of the bSi-F bond. When irradiated with an infrared laser oscillation line near the absorption band of each compound, either as parallel light or lightly focused with a lens, each compound is easily dissociated. The product thus obtained can be separated from unreacted sharp compounds by low-temperature steaming or gas chromatography, and the isotope ratio in Si can be measured using a mass spectrometer.
S1 and 30S1 are concentrated, leaving 2 in the unreacted parent compound.
It can be seen that 8Si is concentrated. In addition, the irradiation wave number is 20 to 50c from the peak of the infrared absorption hand of the parent compound.
For m"', a wave number on the low energy side is suitable; if the wave number is lower than this, the yield of the product will decrease significantly. As for the irradiation temperature, the lower the temperature, the more selectivity can be seen, and the lower the pressure is preferably close to ITorr(;; if the sample pressure is increased too much, the selectivity will decrease.

(Effects of the Invention) According to the present invention, %"Si and 0S1 can be efficiently separated by irradiating the work material containing the fluoromonosilane compound with an infrared laser to separate 81 isotopes, It is effective for the production of Si isotopes, which are in increasing demand in pharmaceutical and agrochemical research and the development of electronic materials.In addition, compared to the mass spectrometry method currently used for Si isotope separation, The laser method has an extremely low manufacturing cost and can provide a large quantity of Si isotopes at low cost.

(Example) The present invention will be described below with reference to Examples. The laser device used was Lumn1cs Co2TI type 103-2.
In the E8 laser device, laser oscillation was performed using a gas mixture of i(e and CO2, or t(e, CO2, and N2). In the case of the former gas mixture, the time width of the laser pulse was Although it is short, the energy of the pulse is small.In the case of the latter gas mixture, the laser pulse oscillates over a long time width, increasing the energy of the pulse several times or more.

FIG. 1 is a schematic diagram of the experimental apparatus ξ used to carry out the present invention. The pulsed laser beam 2 oscillated by the CO2TEA laser device and emitted to the outside is
After passing through a circular iris 3 with a diameter of 1.0 or 1.6 am, the light is guided into a reaction vessel 5 either as parallel light or after being focused by a B a F2 lens 4 . The infrared absorption spectrum of the sample after the laser beam irradiation and after the irradiation is measured by the infrared spectrophotometer 6. After the sample has been irradiated with laser light, the produced S i F is once separated in a low-temperature distillation device 7 and then directly introduced into a mass spectrometer 8 and a gas chromatograph 9 .

First Example> In this example, SiF3CH was used as the working substance (
It was heavily used. Figure 2a shows the racer of this working material)
The pressure of the sample was 1 Torr; the strong absorption band due to the stretching vibration of S+-F near 980 cm-' was 1.
2 Nuraroro Next to this sample)
2) Pulse-like line (942, 38cm-')
The tail was irradiated with parallel light four times. Laser light full-f
The gas was 0.62 J cm-2. The infrared absorption spectrum measured after irradiation with a pulse Vz- of 5000 is shown in the r7' 2 b diagram. Newly appeared 10210
The absorption shoulder near 2O' is due to S i F4.

The irradiation sample '4 was introduced into a gas chromatograph and a mass spectrometer, and the product S i F, 28s1 in
．． The isotope ratio of 2g51.30Si was measured, and the value was
The results are shown in Table 1.
3 i and ``S i are 12.42% and 9.9, respectively.
Concentrated to 4%.

Table i: Cll3S + F3 irradiation (P (22),
Fragment ion intensity and isotope abundance ratio of SiF after parallel light) Experiments were also conducted in the same manner using the same SiF3cH3 as the working material and changing the laser light irradiation conditions. A pulsed laser beam of 942.38 cm-' was generated using a gas mixture of He and CO2 as the laser beam (
10.6μ band, P (22) line) is used. This laser light is attenuated through a polyethylene film, and then focused using a lens with a focal length of 40 cm.
I Torr of 5IF3CH3 was introduced into the reaction vessel filled. The laser fluence at the focal point is 5.
6 J am-'.

The infrared absorption spectrum after irradiation up to 2000 pulses is shown in FIG. 2C. When the sample was introduced into a gas chromatogram and a mass spectrometer and measured, as shown in Table 2, 2981 in SiF was 8.8
7%, 30 S+ was found to be concentrated to 11.19%.

Table 2: Fragment ion intensity and isotopic abundance ratio of S]F4 after irradiation (P (22), focused light) of CH3SiF, second example In this case, SiF3Br is used as a working substance in the department. Ta. A pulsed laser beam (10,6 μ band R(14) line) of 97 L, 93 Cm- was oscillated using a gas mixture of He, CO2, and N2 in a reaction vessel filled with 1 Torr of SiF313r. ) was introduced as parallel light. Laser light fluence is 0.59 JC
m-2, and the number of irradiation pulses was 500. 4th a
Figure 4b shows the infrared absorption spectra after laser light irradiation if1 and 7, respectively. From these graphs, S i F
It is clear that , was generated.

Next, the sample in the reaction vessel after irradiation with laser light was introduced into a force chromatograph and a mass spectrometer. The gas chromatogram obtained at this time is not shown in Fig. 4. Peaks of S i F and S+F3Br appear. Table 3 shows the S i F that has been removed.

The results of mass spectrometry are shown. 2! 15+
,”S i IJ”F:fL sofL6.35%, 7
．． 81% MachiaK6 You can see that it is worn out.

Table 3: S after SiF3Br irradiation (R(14), parallel light)
Fragment ion intensity and isotope abundance ratio of iF

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the experimental apparatus used to carry out the invention, and FIGS. 2a to 2c show S as the working material.
Figures 3a and 3b show infrared absorption spectra before laser irradiation when using iF3CH, and Figures 3a and 3b show infrared absorption spectra before laser irradiation when using SiF and Br as working materials. FIG. 4 is a diagram showing a gas chromatogram after laser beam irradiation when SiF+Br is used as a working substance. DESCRIPTION OF SYMBOLS 1... Laser'-device, 2... Racer light, 3... Iris, 4... Lens, 5... Reaction vessel, 6... ... Infrared spectrophotometer, 7 ... Low temperature distillation device, 8 ... Mass spectrometer, 9 ... Gas chromatography. Figure 30 A number (cm-') Figure 3b Atsushi number (cm")

Claims (6)

[Claims] (1) SiFnX_4_-_n (X is H, Cl, Br,
I, provided that 1≦n≦3) or SiFnR_
A working material for laser isotope separation of Si, which is a fluoromonosilane compound represented by 4_-_n (R is an alkyl group or its halogen derivative, where 1≦n≦3). (2) The working material according to claim (1), wherein the fluoromonosilane compound is a trifluoromonosilane compound. (3) The trifluoromonosilane compound is SiF_3
The working substance according to claim (2), characterized in that it is Br. (4) The trifluoromonosilane compound is SiF_3
Claim No. (2) characterized in that it is CH_3.
) Working materials listed in section 2. (5) SiFnX_4_-_n (X is H, Cl, Br,
I, provided that 1≦n≦3) or SiFnR_
A laser isotope separation method in which a fluoromonosilane compound represented by 4_-_n (R is an alkyl group or its halogen derivative, where 1≦n≦3) is irradiated with an infrared laser to separate Si isotopes. (6) The laser isotope separation method according to claim (5), wherein the infrared laser is a carbon dioxide laser.