The photodissociations of OCS at 157 nm and of CH31(CD,I) at 266 nm have been investigated by using tunable vacuum ultraviolet laser-induced fluorescence and multiphoton ionization to probe the CO or S and the CH,(CD,) or I photoproducts, respectively. In the OCS dissociation, sulphur is produced almost entirely in the S('S) state, while CO is produced in its ground electronic state and in vibrational levels u = 0-3 in the approximate ratio3). The rotational distribution for each vibrational level is found to be near-Boltzmann, with temperatures that decrease from 1350 K for u = 0 to 770 K for v = 3. Measurements of the CO Doppler profiles demonstrate that the dissociation takes place from a transition of predominantly parallel character ( p > 1.3) and that the CO velocity and angular momentum vectors are perpendicular to one another. In the CD31 dissociation, the ratio of CD3 ( u = O)/( u = 2) was estimated to be ca. 1.1, with multiple determinations in the range 0.47-2.1. The quantum number u here denotes the nascent excitation of the u2 'umbrella' mode. A value for the CH, ( u = O)/( u = 2) ratio from dissociation of CH31 could not be estimated, although it was clearly larger than that for CD,. The CH3 ( u = 0) and CD, ( u = 0) products from this dissociation are fitted by 120* 30 K and 105 f 30 K rotational distributions, respectively. The dissociation mechanism produces alignment in the molecular frame such that there is a strong preference for low values of K . Assuming that the relative velocity vector lies along the CH, C3 axis, then the velocity and rotation vectors tend to be perpendicular.
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