Abstract
Relative photodetachment cross sections for rotational thresholds of the hydroxide anion were measured using a coaxial laser-ion beam spectrometer. The thresholds correspond to transitions from the J=1 and J=2 states of X to the J=3/2 state of X OH. Best fits of the data give cross sections that scale with energy above threshold as (E- and (E- for the two thresholds, respectively. This non-Wigner law energy dependence of the cross section results from the long-range interaction between the dipole and the departing electron. Experimental results were compared with the predictions of a strong-coupling model of charge-dipole interaction devised by Engelking and good qualitative agreement was observed. When the resolution and range of the data for transitions that terminate in the lower Λ-doublet component is such that the Λ-doublet splitting is resolved, one observes the (E- behavior predicted by the Wigner law. This result is explained in terms of the effect of the Λ doubling upon the charge-dipole interaction. From the threshold frequencies, an OH electron affinity of 14 741.02(3) was determined.
- Received 26 September 1996
DOI:https://doi.org/10.1103/PhysRevA.55.2036
©1997 American Physical Society