Journal of the Chemical Society, Faraday Transactions
Journal of the Chemical Society, Faraday Transactions; was published from 1990 - 1998. In 1999 it merged with a number of European chemical society physical Chemistry journals to become Physical Chemistry Chemical Physics.
Paper
J. Chem. Soc., Faraday Trans., 1998, 94, 2681 - 2688, DOI: 10.1039/a805103h
Predissociation of the A2
3/2 state of IO studied by cavity ring-down spectroscopyStuart M. Newman, Wendy H. Howie, Ian C. Lane, Mark R. Upson and Andrew J. Orr-Ewing
The IO A2
3/2–X23/2 (v
,0) bands with v=0–5 and the (1,1), (2,1) and (3,1) hot bands have been investigated in absorption using cavity ring-down spectroscopy. Analysis of the spectra gives refined band origins and rotational constants for the v levels and reveals strongly v-dependent predissociation rates for the A23/2 state. Fitting of spectral lineshapes for the rotationally resolved (2,0) band shows that v=2 undergoes a rotation-induced predissociation, most probably via coupling to a 2
- state, with lifetimes for the rotational levels that range from ca. 1 ns at J=1.5 to 15 ps at J=50.5. In contrast, however, the (0,0) and (3,0) bands, which are also rotationally structured, exhibit apparently J-independent predissociation rates. The (1,0), (4,0) and (5,0) bands are sufficiently lifetime-broadened that no rotational structure is evident. Fits to the band contours give average homogeneous (FWHM) linewidths for the various vibrational bands of 0.30±0.03 cm-1 for v=0, 6±1 cm-1 for v=1, 0.80±0.05 cm-1 for v=3, 9±2 cm-1 for v=4 and 60±10 cm-1 for v=5. The dominant predissociation mechanism for v=0,1,3,4, and 5 is attributed to spin–orbit coupling between the A23/2 state and one or more 
=3/2 repulsive states.
