Ultrafast time-resolved soft x-ray photoelectron spectroscopy of dissociating Br2 -: art. no. 193002

The dissociation of excited state Br-2 is probed with the novel technique of ultrafast soft x-ray photoelectron spectroscopy. Excited Br-2 molecules are prepared in the dissociative (1)Pi (u) state with 80 fs, 400 nm pulses, and a series of photoelectron spectra are obtained during dissociation with pulses of soft x-ray light (47 nm, 26.4 eV, 250 fs). The formation of Br atoms is readily detected and the data support an extremely fast dissociation time for Br-2 on the order of 40 fs. Amplitudes of the pump-probe features reveal that the ionization cross section of atomic Br at 47 nm is similar to 40 times larger than that of Br-2.