Photofragmentation of ClNO in the A-Band:  Velocity Distribution and Fine-Structure Branching Ratio of Cl(2P j ) Atoms

The photodissociation of ClNO in the 211−248 nm region has been studied by using photofragment imaging spectroscopy and vacuum ultraviolet laser-induced fluorescence. From the structure of the images of the nascent Cl(2P3/2) and Cl*(2P1/2) atoms, a fragment total translational energy distribution and an anisotropy parameter were derived. Near 235 nm the fragment translational energy distributions exhibit a distinctly bimodal shape. Relative intensities of the slow and fast components vary for two different products, Cl and Cl*. Both components of the Cl* distribution and the major slow component of the Cl state have the anisotropy parameter β = 1.5 ± 0.2 and 1.8 ± 0.2, respectively. The Cl*/Cl branching ratios are 0.93 ± 0.10, 0.45 ± 0.05, and 1.08 ± 0.12 at λ = 213, 235, and 248 nm. The present results provide evidence of strong effects during molecule fragmentation both at internuclear distances close to the equilibrium position due to avoided crossing and at large interfragment separations.