Alignment and velocity distribution of the NO fragments from the UV photodissociation of jet-cooled nitrosobenzene studied by LIF and Doppler profile measurements

摘要

The velocity distribution and alignment of the NO fragments produced by UV photodissociation of nitrosobenzene have been studied by LIF measurements of Doppler profiles and polarization. The S_2 and S_3 states of nitrosobenzene were excited by irradiation into the first and second UV absorption bands at 290 and 266 nm, respectively. No alignment could be detected. All Doppler profiles studied with rotational quantum numbers ranging from j = 6.5 to 29.5 can be fitted by Gaussians, their widths indicating thermal velocity distributions with an average velocity v_(r.m.s.) < 1000 m/s. We interprete this as indication of fast electronic relaxation of the excited nitrosobenzene followed by extensive rotational and vibrational equilibration prior to dissociation.