Study of Photodissociation Dynamics Using Sub‐Doppler Fluorescence Imaging Method: Photodissociation of ICN at 308 nm

Abstract

The sub‐Doppler fluorescence imaging method has been developed to determine velocity distribution, angular distribution, and vector correlation of state‐selected photofragments. Using this new method, photodissociation dynamics can be studied directly in the center‐of‐mass frame, even with an uncollimated molecular beam. We have performed the experiment of photodissociation of ICN at 308 nm to demonstrate that recoil velocities of photofragments can be obtained with out collimating the parent beam. The forward‐ and backward‐scattered CN(X 2Σ+) photofragments are imaged simultaneously for the first time. The recoil velocities of the CN photofragments are measured and the bond dissociation energy D00(I–CN) is determined to be 26960 ± 120 cm‐1, in agreement with the literature values reported recently.

Recombination, Solvation and Reaction of CN Radicals Following Ultraviolet Photolysis of ICN in Organic Solvents

“…The ultraviolet photolysis of ICN is an extensively studied process which has been used to explore nuclear dynamics in electronically excited states and bimolecular reactions of the photofragment CN radical. The dissociation of the I–CN bond in isolated, gas-phase ICN molecules has been directly observed on the femtosecond time scale, − and computational and experimental studies characterized the dissociative electronic potentials − and the resulting quantum-state specific I and CN energy distributions. − The ultraviolet absorption of gaseous ICN peaks at wavelengths around 250 nm, with the broad absorption band structure composed of excitations from the linear 1 Σ + 0 ground state to excited states of 1 Π 1 , 3 Π 0+ and 3 Π 1 symmetry. The 3 Π 0+ state correlates asymptotically with CN (X 2 Σ + ) radicals and spin–orbit excited I*­( 2 P 1/2 ) atoms, but a conical intersection with the 1 Π 1 state provides a nonadiabatic pathway to the lower-lying CN (X 2 Σ + ) + I­( 2 P 3/2 ) asymptote .…”