EFFICIENT ISOTOPE-SELECTIVE IR LASER MULTIPHOTON DISSOCIATION OF ¹¹BCl₃ MOLECULES IN A MIXTURE WITH SF₆ SERVING AS A SENSITIZER AND AN ACCEPTOR OF RADICALS

The results of studies of isotope-selective laser infrared (IR) multiphoton dissociation (MPD) of ¹¹BCl₃ molecules in a natural mixture with ¹⁰BCl₃ by the radiation from a pulsed CO₂ laser in the case of their irradiation with a sensitizer – SF₆ molecules, which are simultaneously acceptors of radicals – Cl atoms formed during dissociation of BCl₃ molecules are presented. A strong increase in the efficiency of dissociation of ¹¹BCl₃ molecules was discovered when they were irradiated with SF₆ molecules compared to the case of irra- diation without SF₆. The main parameters of isotope-selective IR multiphoton dissociation of BCl₃ molecules were measured – the dissociation yields of 11BCl3 (β₁₁) and 10BCl₃ (β₁₀), as well as the selectivity of dissociation of ¹¹BCl₃ molecules relative to 10BCl₃ molecules (α(¹¹B/¹⁰B)). The dependences of these parameters on the pressures of the irradiated gases BCl₃ and SF₆, as well as on the energy density and frequency of the exciting laser radiation were obtained. The main products formed upon irradiation of the mixture of BCl₃ and SF₆ molecules used – SF₅Cl, BCl₂F, BClF₂ and BF₃ – have been identified. A significant (several times) increase in the yield and selectivity of dissociation of ¹¹BCl₃ molecules was observed, as well as a significant decrease in the threshold dissociation energy density when they were irradiated with SF₆ compared to the case of irradiation without SF₆. This opens up the possibility of implementing single-frequency isotope-selective laser MPD of ¹¹BCl₃ molecules in unfocused laser beams at moderate (no more than 4–5 J/cm²) excitation energy density. The results obtained are important and relevant in terms of the application of the described method for the development of laser technology for the separation of boron isotopes.