DYNAMICS OF HIGH-N RYDBERG STATES EMPLOYED IN ZERO KINETIC ENERGY-PULSED FIELD-IONIZATION SPECTROSCOPY VIA THE F-1-DELTA(2), D-1-PI(1), ANDF(3)DELTA(2) RYDBERG STATES OF HCL

The intensity anomalies in the spin-orbit and rotational branching rat ios in the zero kinetic energy pulsed-field ionization (ZEKE-PFI) spec tra via the F (1) Delta(2), D (II1)-I-1, and f (3) Delta(2) Rydberg st ates of HCl have been studied. In general, the branching ratios are ob served to depend on three parameters employed in the pulsed field ioni zation experiment: (i) the delay time between excitation and ionizatio n; (ii) the magnitude of the bias electric field; and (iii) the magnit ude of the applied pulsed electric field. The results can be rationali zed on the basis of the increasing number of autoionization decay chan nels that become available to the high-n Rydberg states as each ioniza tion threshold is surpassed. The delay dependence of the ZEKE-PFI spec tra via the F (1) Delta(2) state has been analyzed in more detail by a b initio calculations. These calculations show that the observed spin- orbit branching ratios can be reproduced thereby giving evidence for a nonexponential decay of the high-n Rydberg states (n approximate to 1 00). (C) 1996 American institute of Physics.