Enrichment of boron, carbon, and silicon isotopes by multiple-photon absorption of 10.6-μm laser radiation

The polyatomic molecules SF6, BCl3, CF2Cl2, and SiF4 have been irradiated in the presence of H2 or N2 using intense focused CO2 laser pulses. All four of the polyatomic molecules underwent isotopically selective reactions showing depletion of the isotopic forms irradiated. The best enrichment was achieved with SF6; however, all systems showed similar behavior with regard to pressure and irradiation time. Both BCl3 and SiF4 showed evidence of isotopic rescrambling reactions that occurred on about a 1-h time scale. The mechanisms of the absorption process are believed to be enabled by the large density of states in the vibrational manifold of polyatomic molecules.