THRESHOLD PHOTOIONIZATION IN HCL

The threshold photoelectron spectrum of HCL shows two bands (2-PI-3/2 and 2-PI-1/2) of unequal intensity and width with partially resolved rotational structure, the 2-PI-1/2 band being about half the 2-PI-3/2 one. Autoionization of Rydberg states with a 2-PI-1/2 core into the 2-PI-3/2 continuum, added to direct ionization, explains the difference observed on the bands which would otherwise be of equal intensities. Direct ionization is observed to proceed according to the rotation spectator model while the autoionization process is due to the combined effects of spin-orbit coupling and L and S uncoupling [Hund's case (e)] yielding high rotational angular momentum transfer DELTA-J less-than-or-equal-to 7/2.