Hs. Carman et al., RYDBERG ELECTRON-TRANSFER TO HYDROGEN IODIDE - DISSOCIATIVE AND NONDISSOCIATIVE ELECTRON-CAPTURE, The Journal of chemical physics, 99(3), 1993, pp. 1734-1743
Rydberg electron transfer (RET) to jet-cooled hydrogen iodide (HI) mol
ecules has been studied for alkali atoms excited to ns and nd Rydberg
levels (9 < n < 40). I- ions produced by dissociative electron capture
are observed for all Rydberg levels studied, even though dissociative
RET becomes endothermic for n < 52. For n > 23, rate constants for I-
formation are in good agreement with previous results for low energy
free electron attachment. For lower values of n, the RET results devia
te from the free electron results due to electrostatic interactions be
tween the nascent positive (Rydberg core) and negative ions. A simple
calculation based upon the ''free electron model'' agrees quantitative
ly with the rate constant data for n > 13. For Rydberg levels with n <
13, long-lived HI- (and DI-) ions are observed which appear to be sta
ble with respect to both dissociation and autodetachment. These observ
ations indicate that a bound and stable anion state exists, correlatin
g with the lowest H (D)+I- limit, with a potential well which supports
at least one vibrational level for both HI- and DI-.