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

Direct measurements of the rate constants for collisional removal of CHF (X ˜ 1 A ′ ( 0,1,0 ) ) by argon (Ar), ethylene (C 2 H 4 ), propene (C 3 H 6 ), 1-butene (1-C 4 H 8 ), iso-butene (i-C 4 H 8 ), 1,3-butadiene (C 4 H 6 ), are reported. CHF (X ˜ 1 A ′ ( 0,1,0 ) ) was prepared by IRMPD of precursor CH 2 F 2 . Fluence independence removal rate constants by Ar, ethylene and propene are: 0.0045, 2.70 and 2.46 × 10 −11 cm 3 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 cm 3 molecule −1 s −1 . Iso-butene has fluence dependence removal rates, given 1.28 and 0.92 × 10 −11 cm 3 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.