ELECTRONIC SPECTROSCOPY OF THE JET-COOLED ARSENIC DICARBIDE (C$_2$As) FREE RADICAL
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Date
2008
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Publisher
Ohio State University
Abstract
The linear arsenic dicarbide (C$_2$As) free radical has been identified by observation of the $^2\Delta$${}$ - $^2\Pi$${}$ band system in the 585.0 - 687.3 nm region by laser-induced fluorescence (LIF) and supersonic expansion cooling techniques. The radical was produced in a pulsed electric discharge jet using a precursor mixture of methane (or acetylene), arsenic trichloride vapor and argon. All three excited state vibrational modes have been identified in the LIF spectra of $^{12}$C$_2$As and $^{13}$C$_2$As. Single vibronic level emission spectra exhibit an isotope-independent ground state spin-orbit splitting of 874 cm$^{-1}$ and activity in the bending and both stretching modes. The measured ground state energy levels have been successfully fitted to a $^2\Pi$${}$ state Renner-Teller model. High resolution spectra of the $0_0^0$ bands of both isotopomers have been recorded and analyzed to obtain the rotational constants and ground and excited state molecular structures. The experimental derived parameters will be compared to {\em ab initio} predictions and experimental data available for the analogous C$_2$N and C$_2$P radicals.
Description
Author Institution: Department of Chemistry, University of Kentucky, Lexington, KY 40506-0055