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Title:Group IIB dimers: Spectroscopy of molecular cadmium and gain demonstration in molecular mercury
Author(s):Tran, Hao Chi
Department / Program:Physics
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Physics, Molecular
Abstract:The $\rm B\sp1\Sigma\sbsp{u}{+}$ state of $\rm Cd\sb2,$ correlated with $\rm Cd(\sp1S)+Cd(5p\ \sp1P\sb1),$ was studied by laser excitation spectroscopy from the lowest metastable state, $\rm a\sp3\Pi\sb{g}.$ The excitation spectrum of the $\rm B\sp1\Sigma\sbsp{u}{+}\gets a\sp3\Pi\sb{g}$ transition in the 555-725 nm spectral range is presented. Birge-Sponner analysis of the $\rm v\sp{\prime\prime}$ = 0,1 vibrational progressions yielded spectroscopic constants for both the $\rm a\sp3\Pi\sb{g}$ and $\rm B\sp1\Sigma\sbsp{u}{+}$ state potentials. Iterative trial and error simulation of the excitation spectrum established the difference between the internuclear separations $\rm (\Delta R\sb{e})$ of the two states. The ultraviolet emission spectra of the $\rm B\sp1\Sigma\sbsp{u}{+}\to X\sp1\Sigma\sbsp{g}{+}$ (bound$\to$free) transition are presented with comparison to the best calculated spectra to determine the $\rm\Delta R\sb{e}$ between the $\rm B\sp1\Sigma\sbsp{u}{+}$ and $\rm X\sp1\Sigma\sbsp{g}{+}$ states.
$\rm GO\sbsp{u}{+}\to XO\sbsp{g}{+}$ bound-free emission spectra of $\rm Hg\sb2$ from several different vibrational levels were analyzed to determine the (1) $\rm\Delta R\sb{e}$ between the $\rm GO\sbsp{u}{+}$ and $\rm XO\sbsp{g}{+}$ states, and (2) the region of internuclear separative over which the mostly dissociative ground state is bound. Photoassociative excitation spectrum is shown for the 265-285 nm spectral region which corroborates the emission data concerning the ground state.
Gain on the $\rm GO\sbsp{u}{+}\to XO\sbsp{g}{+}$ transition was observed at ${\sim}227$ nm when a prepared population of $\rm Hg\sb2$ in the metastable $\rm AO\sbsp{g}{+}$ state is pumped with 564.3 nm radiation. This represents an anti-Stokes shift of ${\sim}3.3$ eV of the pump radiation and confirms the reality of a population inversion between the $\rm AO\sbsp{g}{+}$ (storage) state and the dissociative $\rm XO\sbsp{g}{+}$ ground state.
Issue Date:1997
Rights Information:Copyright 1996 Tran, Hao Chi
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9717339
OCLC Identifier:(UMI)AAI9717339

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