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

The photodissociation dynamics of n-alkyl bromides R-Br (R = n-alkyl radical) (C2H5Br, n-C3H7Br, n-C4H9Br, n-C5H11Br) 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(P-2(3/2))(denote Br)/Br(P-2(1/2)) (denote Br*). The branching ratios N(Br*)/ N(Br) and the relative quantum yields (p(Br*) and phi(Br) were determined. The results indicated the ground-state bromine was the major dissociation product in this wavelength region. The (p(Br*) at 234 nm were, in general, larger than that 267 nm. The yields (p(Br*) showed an increasing tendency from C2H5Br to n-C5H11Br at 234 nm and a little change at 267 nm. Compared with the dissociation of CH3Br, a qualitative explanation was presented for the photodissociation of n-alkyl bromide. (C) 2004 Elsevier B.V. All rights reserved.