Laser optoacoustic method for measuring relative isotopic abundances of molecules

A description is given of a method for measuring the relative abundances of isotopes in molecules with the aid of laser spectrophones. The basis of the method is the use of laser radiation of two frequencies and a periodic comparison of the signals produced by two spectrophones. The apparatus employed is described. The results are given of an experimental determination of changes in the ratio of the abundances of the ¹⁰B and ¹¹B isotopes. The question of the maximum sensitivity of the proposed method is considered. In principle, the use of lasers with output powers of about 1 W should make it possible to measure deviations down to 10^–4% from the standard isotopic composition of a molecule.