Selective IR Laser Induced Isomerization and Dissociation of BIS (Trifluoromethyl) Ketene Molecules

Abstract

Multiphoton IR laser induced isomerization and dissociation of (CF3)2C=C=O (FMK) molecules have been studied. The antisymmetric stretch v1 = 2192 cm-1 of C=C=O—and antisymmetric v16 = 991 cm-1 of C—C— bonds were excited by the second- and first harmonics of a pulsed TEA CO2 laser. The dependence of isomerization conversion on laser radiation frequency, fluence, and number of shots was measured. The isomerization channel was predominant compared with dissociation for the conditions of IR multiphoton excitation under study.The isomerization of FMK by the second–harmonic radiation of a CO2 laser was proved to be selective with respect to oxygen isotopes. The isomerization product (FMA molecules) was enriched with 18O with maximum value of selectivity α(18/16) = 3.9 when FMK molecules were excited at 2ωlas = 2143.8 cm-1.