Two- and three-body photodissociation dynamics of diiodobromide (I2Br-) anion

The photodissociation of gas-phase I2Br- was investigated using fast beam photofragment translational spectroscopy. Anions were photodissociated from 300 to 270 nm ( 4.13-4.59 eV) and the recoiling photofragments were detected in coincidence by a time- and position-sensitive detector. Both two- and three-body channels were observed throughout the energy range probed. Analysis of the two- body dissociation showed evidence for four distinct channels: Br- + I-2, I- + IBr, Br + I- 2, and I + IBr-. In three-body dissociation, Br(P-2(3/2)) + I(P-2(3/2)) + I- and Br- + I(P-2(3/2)) + I(P-2(3/2)) were produced primarily from a concerted decay mechanism. A sequential decay mechanism was also observed and attributed to Br-(S-1) + I-2(B-3 Pi(+)(0u)) followed by predissociation of I-2(B). (C) 2011 American Institute of Physics. [doi: 10.1063/1.3571474]