Knowledge Bank

The first singlet state of bromobenzene $(1B1\leftarrow 1A1)$ has been observed in a skimmed supersonic molecular beam. A doubled dye laser, pumped by a Nd: YAG laser, produces the ionization spectra in the region of 2700 {\AA}-2550 {\AA}. The ions produced were detected using a flow-through time of flight mass spectrometer. Ionization occurs in a sequential two photon absorption. The first photon is resonant with vibrational features in the singlet state. A second photon is absorbed to produce predominantly parent ions. Vibrational features are assigned in the $S1$ state. Ion branching ratios are presented as a function of wavelength and evidence for predissociative channels are discussed.