Energy Transfer Kinetics of N2(X ,v) and SiH4

Abstract

We have studied the kinetics of N2(X,v) with silane. These experiments were done in a discharge-flow reactor and used N2(X,v) diagnostics employing metastable energy transfer reactions. To investigate vibrational levels greater than five, and up to at least thirteen, we analyze N2(B3Πg,v‘≤12) fluorescence excited in the interaction between metastable N2(A3 ) and N2(X1 ,v). N2+ (B2 ,v‘=0−8) fluorescence, excited when metastable helium atoms collide with N2(X,v), diagnoses vibrational levels between one and six. The rate coefficients for quenching vibrationally excited nitrogen by silane range from 1 × 10-13 to 6 × 10-13 cm3 molecule-1 s-1, being higher for the higher vibrational levels. Observations at 4500 nm show that at least one channel for the N2(X,v) quenching process involves excitation of SiH4(ν3). Comparison of the relative excitation rate of SiH4(ν3) with that for N2O(ν3) excitation when N2O is added to the reactor, however, indicates that at most 15% of the N2(X,v) quenching events result in ν3 excitation. Presumably the rest of the energy is absorbed by other vibrational modes.