Rotationally resolved photoionization dynamics of hot CO fragmented from OCS

The photoionization dynamics of rotationally 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 (D-1) atoms. These high rotational levels show photoelectron spectra with a very strong DeltaN=0 transition and weaker DeltaN=+/-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 Deltav=0, but also off-diagonal, non-Franck-Condon (Deltavnot equal0) 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 (2)Pi core. (C) 2002 American Institute of Physics.