DOUBLE RESONANCE EXCITATION OF THE RUBIDIUM DIMER : THE 2 $^{1}\Pi_g$ STATE
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Date
2013
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Publisher
Ohio State University
Abstract
We have performed a series of optical-optical double resonance experiments with one or two cw Ti:sapphire lasers, to excite the 2~$^{1}\Pi_g$ state of Rb$_2$, recording infrared fluorescence from 2~$^{1}\Pi_g$ on a Fourier transform spectrometer. Fluorescence from the lower vibrational levels of 2~$^{1}\Pi_g$ (T$_e$ = 22069.56 cm$^{-1}$) is dominated by transitions to the B $^{1}\Pi_u$ state studied by Amiot and Verges, Chem. Phys. Lett. 294, 91-98 (1997). Vibrational and rotational relaxation from laser-pumped levels v' $<$ 15 now give a rather complete description around the potential minimum of the 2~$^{1}\Pi_g$ state, completing the observations for 6 $\leq$~v~$\leq$ 50 reported by Han et al, Chem. Phys. Lett. 538, 1-4 (2011) last year. Fluorescence from v' $>$ 35, occurs also to the 0$^+$ components of the A~$^{1}\Sigma_u^+ \sim $b$~^{3}\Pi_u $ complex. Fitting all available 2~$^{1}\Pi_g \rightarrow $B~$^{1}\Pi_u $ data for $^{85}$Rb$_2$ and $^{85}$Rb$^{87}$Rb (several thousand transitions) has also given an improved description of the bottom of the B $^{1}\Pi_u$ state potential well. The 2~$^{1}\Pi_g$ state correlates at long-range with Rb 5s + Rb 4d $^2D_{3/2}$ atoms (A.-R. Allouche, M. Aubert-Frecon, J. Chem Phys 136, 37-41 (2012)), giving a dissociation energy of 1279.6 cm$^{-1}$. Most new data lie below v = 45, 250 cm$^{-1}$ below this dissociation threshold.
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Author Institution: Department of Chemistry, Moscow State University, 119991; Moscow, Russia\; Institut Lumiere Matiere, Universite Lyon 1 \& CNRS UMR5306, Universite de Lyon, France