T/D isotope selectivity in CO₂ laser induced multiple-frequency multiphoton dissociation of trifluoromethane-T

Abstract

Isotope-selective multiphoton dissociation of CTF₃ in the presence of CDF₃ by TEA CO₂ laser is studied. The highest T/D selectivity of 58 was observed at a sample pressure of 2 Torr in the presence of 20 Torr of argon on excitation by the 9P(24) CO₂ laser line. The effect of multiple-frequency irradiation on selectivity is studied in the P and Q branches of the ν₂ absorption band of CTF₃. No improvement in the selectivity is noticed on going from single- to multiple-frequency irradiation. These results are compared with previous multiple-frequency work on the CTF₃/CHF₃ system, and explained in terms of strong spectroscopic interference from ¹³CDF₃ in the present case.