HIGH SENSITIVITY CRDS OF THE $a^{1}\Delta_{g}$$\leftarrow$$X^{3}\Sigma^{-}_{g}$ BAND OF OXYGEN NEAR 1.27 $\mu$m: MAGNETIC DIPOLE AND ELECTRIC QUADRUPOLE TRANSITIONS IN SPECTRA OF FIVE ISOTOPOLOGUES
Loading...
Date
2010
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The knowledge of accurate spectroscopic parameters for the $a^{1}\Delta_{g}$$\leftarrow$$X^{3}\Sigma^{-}_{g}$ band of molecular oxygen near 1.27 $\mu$m is very important in the field of remote sensing. Although this band was studied by spectroscopists for over a century a lot of discrepancies still remain in the previously reported line positions and intensities. In this work the Continuous Wave-Cavity Ring Down Spectroscopy (CW-CRDS) technique has been used to record with high sensitivity the absorption spectrum of this band. The spectra were obtained between 7640 and 7917 cm$^{-1}$ with ``natural'' oxygen and with a sample highly enriched in $^{18}$O. The absolute intensities of 377 and 652 oxygen transitions were measured in the two spectra, respectively. They include the $a^{1}\Delta_{g}$$\leftarrow$$X^{3}\Sigma^{-}_{g}$ (0-0) bands of $^{16}$O$_{2}$, $^{16}$O$^{18}$O, $^{16}$O$^{17}$O, $^{17}$O$^{18}$O and $^{18}$O$_{2}$. The (0-0) bands of $^{16}$O$_{2}$ and $^{18}$O$_{2}$ show (previously undetected) electric quadrupole transitions with line intensities ranging from 1$\times$10$^{-30}$ to 1.9$\times$10$^{-28}$ cm/molecule. They are accompanied by the $a^{1}\Delta_{g}$$\leftarrow$$X^{3}\Sigma^{-}_{g}$ (1-1) hot bands which are also reported for the first time. Accurate spectroscopic parameters for the observed bands were derived from a global fit of the experimental line positions, combined with microwave and Raman measurements available in the literature.
Description
Author Institution: Universite Joseph Fourier/CNRS, Laboratoire de Spectrometrie Physique, 38402 Saint Martin d'Heres, FRANCE; Harvard-Smithsonian Center for Astrophysics, Atomic and Molecular; Physics Division, Cambridge MA 02138-1516, USA; Universite Joseph Fourier/CNRS, Laboratoire de Spectrometrie Physique, 38402 Saint Martin d'Heres, FRANCE