Rotationally resolved photoionization dynamics of hot CO fragmented from OCS

摘要

The photoionization dynamics of rotastionally hot CO, photodissociated from OCS, have been studied using laser photoelectron spectroscopy via the intermediate B ~1#SIGMA#~+ Rydberg state leading to the X ~2#SIGMA#~+ of the ion. THe photodissociation of OCS near 230 nm produces rotationally hot, but vibrationally cold CO (X ~1#SIGMA#~+, N", v"=0,1) fragments along with S (~1D) atoms. These high rotational levels show photoelectron spectra with a very strong #DELTA#N=0 transition and weaker #DELTA#N = +-1, +-2, and +-3 transitions. Agreement between measured and calculated spectra is good and suggests that there is significant angular momentum coupling in the photoelectron orbital. In the ionization step not only #DELTA#v=0, but also off-diagonal, non-Franck-Condon (#DELTA#v not= 0) transitions are observed. The intensities of these transitions vary strongly within the region studied and can be explained by the excitation of superexcited Rydberg states with an A ~2II core.