ANALYSIS OF THE $3^{1} A'$ STATE OF HCP
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Date
1994
Journal Title
Journal ISSN
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Publisher
Ohio State University
Abstract
The predissociated $3^{l} A^{\prime}$ state of HCP, whose origin is at $50642.18\pm 09 cm^{-1}$, has been observed for the first time in fluorescence-dip detected optical-optical double resonance spectra excited using selected single rovibronic levels of the $A^{1} A^{\prime\prime}$ state of HCP as intermediate level. The bending vibration $(\nu_{2})$ appears to be extremely anharmonic, with the spacings between successive members of the bending progression {increasing} for a given value of the $k_{a}$ quantum number. A rapid increase in the A rotational constant with $v_{2}$ has also been observed, in combination with an increase in the ratio $\Delta (1,0)/\Delta E(2,0)$ [where $\Delta E(i,j)$ is the spacing between the $K_{a} = $i and j levels] from a value close to the value of 0.25 that is typical for an ideal bent molecule. This ratio would have a value close to 0.5 in the linear limit. These effects seem consistent with quasilinear and/or Renner-Teller behavior of the $3^{l}A^{\prime}$ state. {Ab initio} $calculations^{1}$ suggest that the $3^{1}A^{\prime}$ potential surface arises form a conical intersection between the lower component of the Renner-Teller split $n \rightarrow \pi^{1}\Pi$ state and the quasilinear $\pi^{2} \leftarrow \pi^{2} 2^{1} \Sigma^{+}$ state. The rotational quasilinear/Renner-Teller behavior will be presented.
Description
$^{1}$S. P. Kama, P. J. Bruna, and F. Grein, Canad. J. Phys. 68 499 (1990)
Author Institution: Department of Chemistry, M.I.T.; Department of Chemistry, M.I.T.; Department of Chemistry, National Taiwan University; Department of Chemistry, M.I.T.; Department of Chemistry, M.I.T.
Author Institution: Department of Chemistry, M.I.T.; Department of Chemistry, M.I.T.; Department of Chemistry, National Taiwan University; Department of Chemistry, M.I.T.; Department of Chemistry, M.I.T.