ANOMALOUS AUTOIONIZATION LIFETIMES OF RYDBERG STATES IN A CIRCULARLY-POLARIZED MICROWAVE FIELD

Recent experiments by Jones, Fu, and Gallagher [J. Chem. Phys. 106, 35 78 (1997)] designed to mimic collisional effects on the lifetimes of Z EKE Rydberg states find that, in a circularly polarized microwave fiel d, autoionization lifetimes of atomic Rydberg states exceed those in a linearly polarized field. Surprisingly, however, the lifetimes not on ly do nor display the expected n(5) scaling but are essentially indepe ndent of n for most of the states prepared in the experiment. Similar observations were made by Vrakking and Lee [J. Chem. Phys. 102, 8818 ( 1995)] in studies of NO Rydberg states. We present a classical model t hat predicts n-independent behavior of autoionization lifetimes over e ssentially the same range of It-values as in the experiments of Jones, Fu, and Gallagher. The origin of this behavior is traced to the parti cular combinations of field strengths and frequency used in the experi ment. (C) 1998 American Institute of Physics.