Alignment of CN from 248 nm photolysis of ICN: A new model of the <i>A</i> continuum dissociation dynamics

Abstract

A KrF excimer laser (248 nm) is used to dissociate a low pressure (5–10 mTorr) sample of cyanogen iodide (ICN) and the resulting CN X 2Σ+ fragments are probed by laser-induced fluorescence (LIF) via various vibrational sequences of the B 2Σ+–X 2Σ+ transition. In addition to measuring relative vibrational and rotational populations in the CN X 2Σ+ photofragment, the alignment of rotational angular momentum in this fragment is determined from the variation in LIF intensity as the direction of linear polarization of the probe laser is rotated with respect to that of the photolysis laser. A unifying model is proposed for the à continuum photodissociation dynamics which is able to account for present and previous experimental measurements characterizing both the I and CN photofragments.