The photodissociation dynamics of ICN at 304.67 nm by state-selective one-dimensional translational fragmentation spectroscopy.

The photodissociation dynamics of ICN to CN+I(2P3/2) are investigated by state selective one-dimensional photofragmentation translation spectroscopy at 304.67 nm. Translational energy release, laboratory anisotropy factors, and energy distributions are obtained from analysis of the velocity and spatial distributions of the photodissociated iodine atoms. Two velocity distributions peaks are deconvoluted which are found to be separated by 2000 cm-1, which is the CN stretching vibration of the CN radical. The high intensity velocity peak is assigned to dissociation to I+CN(X 2Σ+) in v=0 (channel I), while the weak lower velocity peak is attributed to dissociation to I+CN(X 2Σ+) in v=1 (channel II). More than 80% of the iodine are produced from channel I and are found to have a relatively small anisotropy parameter, β, that is independent of velocity, suggesting a mixed absorption polarization leading to rapid dissociation. The weak shoulder, representing less than 20% of the photodissociated iodine, is formed via channel II and found to have a β value that decreases with velocity and produces CN with more of the available excess energy appearing in rotation, suggesting longer dissociation time that allows for more energy redistribution prior to dissociation. The dissociation mechanisms involved in these two channels are discussed in terms of these results, the theoretically predicted properties of the 3Π+0 and 3Π1 surfaces of ICN, our previous conclusion that suggests that ICN bends prior to dissociation via channel II, the laser wavelength used, and curve crossing between the 3Π+0 and 1Π1 surfaces. [ABSTRACT FROM AUTHOR]