V → R, T energy transfer processes in vibrationally excited pentafluorobenzene using a Hg tracer absorption method

Abstract

A new technique based upon the Doppler and Lorentz broadening of the isotopic and hyperfine Hg multiplet lines near 254 nm was used to monitor the translational equilibration of vibrationally excited pentafluorobenzene (PFB). Excitation was achieved with a pulsed CO 2 infrared laser focused into a cell containing PFB and a trace amount of Hg. Rates of V→ R, T energy transfer were found to be linearly dependent on both the excitation energy and the pressure of PFB. Excitation energies were independently determined by the Hg absorption technique and by measuring the change in absorption by the PFB at 254 nm. For PFB ∗-PFB ∗ collisions, the average energy transferred per collision divided by the average excitation energy of the colliding pair, 〈Δ〉/ 〈 E〉, is0.0133±0.0016.