MAGNETIC DIPOLE TRANSITIONS IN DIATOMIC MOLECULES: SOME NEGLECTED ASPECTS
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Date
1988
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Ohio State University
Abstract
A diatomic molecule in the vibronic state $|\Delta s\Sigma;v>$ has a dominant magnetic moment given by $(\Delta+2\Sigma)$ (eh/4nmc) due to which weak rotational transitions within this state are possible. Magnetic dipole transitions of this kind are $known^{1}$ in the $X^{3}\Sigma_{g}^{-}$ state of $0_{2}$. Extending the results to other electronic states, expressions for the intensity factors are derived for rotational transitions in $^{2}\Delta$ and $^{3}\Delta$ states. A noteworthy feature is that both parallel and perpendicular moments can contribute to the rotational intensities. An allied aspect, perhaps more interesting, is that the magnetic moment in the state $|\Delta s\Sigma;r>$ has no dependence on the internuclear distance. Thus in a given electronic state rotation- vibration transitions of magnetic dipole origin seem forbidden notwithstanding the occurrence of pure rotational transitions. Nevertheless one could invoke indirect mechanisms that can impart non-zero intensities to ro-vibrational transitions. In the simplest case of a $^{1}\Delta (\Delta + 0)$ state centrifugal distortion is one such mechanism. In states of higher multiplicity other mechanisms are conceivable. Possible application of these results will be indicated.
Description
$^{1}$ L.R. Zink and M. Mizushima, J.Mol. Spectrosc. 125, 154 (1987).
Author Institution: Spectroscopy Division, Bhabha Atomic Research Centre, Modular Laboratories
Author Institution: Spectroscopy Division, Bhabha Atomic Research Centre, Modular Laboratories