Direct Measurements of Removal Rates of CHF(X˜1A′(0,1,0)) by Simple Alkenes

Abstract

Direct measurements of the rate constants for collisional removal of CHF(X˜1A′(0,1,0)) by argon (Ar), ethylene (C₂H₄), propene (C₃H₆), 1-butene (1-C₄H₈), iso-butene (i-C₄H₈), 1,3-butadiene (C₄H₆), are reported. CHF(X˜1A′(0,1,0)) was prepared by IRMPD of precursor CH₂F₂. Fluence independence removal rate constants by Ar, ethylene and propene are: 0.0045, 2.70 and 2.46 × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹, faster than the rates for the vibrational ground state. 1,3-butadiene was measured at a fluence of 42Jcm⁻², yielding a value of 0.81 × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹. Iso-butene has fluence dependence removal rates, given 1.28 and 0.92 × 10⁻¹¹ cm³ molecule⁻¹ s⁻¹ for fluences of 50 and 32Jcm⁻² respectively. For 1-butene a non-linear Stern-Volmer behaviour has been observed and attributed to fast resonant vibrational-to-vibrational (V-to-V) intermolecular energy transfer. The influence of this (V-to-V) energy transfer on the removal rates is discussed.