PHOTOCHEMICAL SEPARATION OF ISOTOPES

In almost all existing methods of isotope separation, the enrichment coefficient of a single cascade of a separation unit is a function of the ratio of the isotope masses and usually varies within the range from 1.1 to 1.006. The photochemical method of isotope separation proposed by the authors*) makes it possible to attain an enrichment coefficient equal to 1.5.

The photochemical method of separation is based on the well-known fact that the probability of a chemical reaction occurring between excited atoms is greater than between unexcited ones. For isotope separation by the method proposed by the authors, the following conditions must be fulfilled:

1) The absorption spectra of the two isotopes must be clearly shifted relative to one another.

2) The light source used to excite the isotopes by irradiating the mixture to be separated must emit very narrow spectral lines, so as to excite only one isotope in the mixture.

3) It is necessary to find a chemical reaction in which the excited atoms participate and the unexcited ones do not.

The authors applied this method to isolate the mercury isotope \( \mathrm{Hg}^{198} \). They used the 2537 Å line of a mercury lamp with the mercury isotope \( \mathrm{Hg}^{198} \). The process of isolating the mercury isotope \( \mathrm{Hg}^{198} \) from a mixture of isotopes takes place in a special chamber by means of a reaction with water vapor, proceeding, apparently, according to the scheme:

\[ \mathrm{Hg}^{*} + \mathrm{H}_{2}\mathrm{O} \to \mathrm{HgH} + \mathrm{OH}, \]

\[ \mathrm{HgH} + \mathrm{OH} \to \mathrm{HgO} + \mathrm{H}_{2}, \]

or

\[ \mathrm{Hg}^{*} + \mathrm{H}_{2}\mathrm{O} \to \mathrm{HgO} + \mathrm{H}_{2}, \]

where the asterisk denotes an excited mercury atom, i.e., the isotope \( \mathrm{Hg}^{198} \). \( \mathrm{Hg}^{198}\mathrm{O} \) is separated from the mixture by chemical means.

Yu. B.