High-resolution one-photon absorption spectroscopy of the $D{}^2{\Sigma }^{-}\leftarrow X{}^2\Pi$ system of radical OH and OD

Abstract

Vacuum-ultraviolet (VUV) photoabsorption spectra were recorded of the $A{}^2{\Sigma }^{+}(v^{\prime }=0)\leftarrow X{}^2\Pi (v^{\prime \prime }=0)$, $D{}^2{\Sigma }^{-}(v^{\prime }=0)\leftarrow X{}^2\Pi (v^{\prime \prime }=0)$ and $D{}^2{\Sigma }^{-}(v^{\prime }=1)\leftarrow X{}^2\Pi (v^{\prime \prime }=0)$ bands of the OH and OD radicals generated in a plasma-discharge source using synchrotron radiation as a background continuum coupled with the VUV Fourier-transform spectrometer on the DESIRS beamline of synchrotron SOLEIL. High-resolution spectra permitted the quantification of transition frequencies, relative $f$-values, and natural line broadening. The $f$-values were absolutely calibrated with respect to a previous measurement of $A{}^2{\Sigma }^{+}(v^{\prime }=0)\leftarrow X{}^2\Pi (v^{\prime \prime }=0)$ ([wang1979]). Lifetime broadening of the excited $D{}^2{\Sigma }^{-}(v=0)$ and $D{}^2{\Sigma }^{-}(v=1)$ levels is measured for the first time and compared with previous experimental limits, and implies a lifetime 5 times shorter than a theoretical prediction ([van_der_loo2005]). A local perturbation of the $D{}^2{\Sigma }^{-}(v=0)$ level in OH was found.

References in corpus (2)

• Photoprocesses in protoplanetary disks
• Shielding by Water and OH in FUV and X-ray Irradiated Protoplanetary Disks