Measurement of photolysis branching ratios of 2-bromopropane at 234 and 267Â nm

The photolysis branching ratios of 2-bromopropane have been investigated near 234 and 267 nm using resonance-enhanced multiphoton ionization with time of flight mass spectrometry. Bromine fragments monitored in this study were produced via direct dissociation of 2-bromopropane, represented by CH3CHBrCH3 → CH3CHCH3 + Br(2P3/2)/Br*(2P1/2). The branching ratios at two different excitation wavelengths were measured to be 0.534 and 0.244, respectively. The results indicated that the Br(2P3/2) dominated the dissociation process and the branching ratios exhibited an increasing trend with photon energy increase. Through ab initio calculation, we proposed a possible photodissociation mechanism of 2-bromopropane.