OBSERVATION OF $\Omega = 1/2$ STATES IN NiH THROUGH COLLISIONALLY INDUCED FLUORESCENCE
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Date
2011
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Publisher
Ohio State University
Abstract
Fourier transform spectra of collisionally induced fluorescence following isotopically selective laser excitation of NiH at $\sim 550$~nm has allowed us to locate an exited $\Omega' = 1/2$ state of NiH lying 17900~cm$^{-1}$ above the electronic ground state. We identify this as $v = 0$ of a $^2\Pi_{1/2}$ state, originating from the Ni$^+$ $3d^84s^1$ $^2$F configuration, from the ab initio studies published by Zou and Liu in 2007. Emission from the [17.9]0.5 state occurs to $v''= 0$ and 1 of the $^2\Sigma^+$ and $^2 \Pi_{1/2}$ low-lying ligand field states, locating hitherto elusive $^2 \Pi_{1/2}$ $f$ parity levels to within 0.01~cm$^{-1}$. Collisionally induced fluorescence following laser excitation at lower energies has been recorded in the presence of a magnetic field (0.7~$-$~1~Tesla), at Doppler resolution. The partially resolved Zeeman patterns have been used to derive effective Lande factors $g_J$ for the $v=0$ and 1 levels of the low-lying $\Omega'' = 5/2$ and $3/2$ states (${^2\Delta}$ and $^2\Pi$ states from Ni$^+$ $3d^9$). These are compared with predictions from a revised fit of zero-field energy levels, now including the new observations concerning the $\Omega'' = 1/2$ states.
Description
Author Institution: Universite Lyon 1; CNRS; LASIM UMR 5579, 43 Bd du 11 novembre 1918, F-69622 Villeurbanne, France; Department of Physics and Center for Laser, Atomic, and Molecular Sciences, University of New Brunswick, Fredericton, Canada E3B 5A3