Photodissociation dynamics of n-alkyl bromide at 234 and 267 nm

Abstract

The photodissociation dynamics of n-alkyl bromides R–Br (R= n-alkyl radical) (C 2H 5Br, n-C 3H 7Br, n-C 4H 9Br, n-C 5H 11Br) were investigated near 234 and 267 nm using resonance-enhanced multiphoton ionization (REMPI) with time of flight mass spectrometry (TOF-MS). Bromine fragments monitored in this study were produced via direct dissociation of R–Br, represented by R–Br → R + Br( 2P 3/2)(denote Br)/Br( 2P 1/2) (denote Br *). The branching ratios N(Br *)/ N(Br) and the relative quantum yields ϕ(Br *) and ϕ(Br) were determined. The results indicated the ground-state bromine was the major dissociation product in this wavelength region. The ϕ(Br *) at 234 nm were, in general, larger than that 267 nm. The yields ϕ(Br *) showed an increasing tendency from C 2H 5Br to n-C 5H 11Br at 234 nm and a little change at 267 nm. Compared with the dissociation of CH 3Br, a qualitative explanation was presented for the photodissociation of n-alkyl bromide.