화학공학소재연구정보센터
Journal of Chemical Physics, Vol.108, No.8, 3178-3186, 1998
Photodissociation studies on nitrosyl bromide: I. Photofragment spectroscopy and electronic structure
The UV-visible absorption spectrum of nitrosyl bromide (BrNO) was recorded. The spectrum exhibits several broad features in the 200-730 nm region. To aid the assignment of the spectrum, photodissociation experiments were carried out at several selected excitation wavelengths. Resonance-enhanced multiphoton-ionization spectra of both the NO and Br fragments as well as photofragment time-of-flight profiles were recorded. The electronic transitions were assigned based on the observed spatial anisotropy parameters (beta), the Br spin orbit state population, and NO rotational, vibrational, spin-orbit, Lambda-doublet state populations, as well as comparisons with isovalent ClNO system. The strongest UV band peaked around 210 Mm was attributed to the parallel S-5 <--S-0 transition (sigma*(Br-N)<--sigma(Br-N)) while all other features at longer wavelengths were assigned to transitions to excited triplet states. The intensity borrowing from the S-5 State is responsible for the apparent parallel nature of these singlet-triplet transitions. Implications of this assignment on the electronic structure and the non-adiabatic dissociation dynamics are discussed.