ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
An ab initio configuration interaction (CI) study including the spin–orbit interaction is carried out for numerous valence and Rydberg states of the AsH radical by employing a relativistic effective core potential for the arsenic atom. The computed spectroscopic constants are in good agreement with corresponding experimental data, with a tendency toward a slight overestimation of bond lengths (by 0.01–0.02 Å) and Te values (by 450–550 cm−1) for the lowest singlet states. Measured spin–orbit splittings for the X 3Σ− and A 3Π multiplets are also accurately reproduced in the present calculations and the Ω=0−, 1, and 2 components of the latter state are shown to be strongly predissociated due to spin–orbit interaction with the corresponding components of the repulsive 5Σ− state. Dipole moments μ(v=0) for the lowest-lying X 3Σ−, a 1Δ, and b 1Σ+ states, all arising from the (centered ellipsis)σ2π2 electronic configuration, are computed to have small (e.g., 0.1266 D for X1 3Σ0+−) and nearly equal positive values (As−H+ polarity). This finding is used to explain why the partial radiative lifetime for the parallel b–X1 transition (τp=44 ms) is much longer than that (τp=0.95 ms) of the perpendicular b–X2. The lifetime of the a 1Δ state is calculated to be 97 ms, significantly longer than that of the b 1Σ+ state, while the A 3Π substates have much shorter lifetimes (≤1 μs) for radiative decay to the X 3Σ− ground state. A number of other bound states and avoided crossings are indicated in the calculations which may be of relevance in future experimental studies of this system. © 1998 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.475582
