OSCILLATOR STRENGTHS IN THE VISIBLE ABSORPTION SPECTRUM OF I$_2$
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Date
2010
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Ohio State University
Abstract
The $B-X$ transition in I$_2$ stands as one of the most precisely characterized diatomic electronic systems, with thousands of lines having been measured with precision sufficient to serve as frequency standards across the 500-700-nm spectral region. Accordingly the molecular constants of the $B-X$ system permit recalculation of those line positions with similar precision (~0.001 cm$^{-1}$). Yet the $B-X$ electronic transition strength remains a ~10-percent quantity, in part from the difficulty of dealing with two overlapping continuous 1u-$X$ transitions, $A-X$ and $C-X$. In this work, oscillator strengths are estimated from a long-known but little used method -- integration of absorption cross sections over single rotational lines -- using measurements obtained for lines near 650 nm with a diode laser. The results are combined with new, precise low-resolution (1 nm) absorption data to obtain a refined assessment of electronic transition strengths in the I$_2$ visible absorption spectrum.
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Author Institution: Department of Chemistry, Vanderbilt University, Nashville, TN 37235