Vibrational energy transfer in the two-channel 1,1-cyclopropane- d2 isomerization system. Krypton bath gas

Abstract

The study of intermolecular energy transfer in the 1,1-cyclopropane- d 2 system has been repeated for the neat gas at 973 K and has been extended to krypton bath gas at 823 K and 973 K. The method of study is by the competitive collisional activation “spectroscopy” technique for this two-channel competitive isomerization system. Results at 823 K give the relative collisional efficiency of krypton as β ≈ 0.46, at k/k ∞ ≈ 0.02 and yield the average down-jump energy step as 〈Δ E〉 ≈ 1200 cm −1 on the basis of a stepladder model for the distribution of down-step sizes. At 973 K and k/k ∞ = 0.02, β ≈ 0.07 and 〈Δ E〉 ≈ 500 cm −8, for both an exponential and stepladder distribution of down-step sizes. Agreement with related earlier data for other bath gases and for neat cyclopropane is good and verifies again a decrease in energy transfer collisional efficiency, and a decrease in 〈Δ E〉, with rise of temperature, as previously reported for this system.