INFRARED DIODE LASER SPECTRUM OF THE $V_{11}$ BAND OF $NO_{2}$ DIMER
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Date
1992
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Ohio State University
Abstract
The nitrogen dioxide dimmer, ($NO_{2}$)$_{2}$, has been known for some time to exist in significant concentration at room temperature, in equilibrium with its monomeric form. This is due to a relatively high bond energy ($\Delta h=-53.2 KJ mol^{-1}$), intermediate between those of van der waals complexes and those of typical chemical bonds, However, no high resolution spectroscopie studies in the gas phase have been reported so far, presumably due to the highly congested spectrum at room temperature. (Just before submitting this abstract, we received information from the group at the Laboratoire de chimie physique moleculaire at the Universite Libre de Bruxelles that they have recorded a jet-cooled FTIR spectrum of some bands of ($NO_{2}$)$_{2}$. See communication by M. Herman). We have recorded the sub-Doppler, jet-cooled spectrum of the $V_{11}$ ($b_{3{u}}$ band at $1263 cm^{-1}$, by diode laser absorption. The diode laser beam crosses the jet formed in the continous expansion expansion of a $NO_{2}$/Ar mixture through a slit nozzle in a double pass configuration. Most $(NO_{2})_{2}$ lines are fully resolved and observable with a high S/N. A description of the apparatus together with the results of the analysis presently underway will be presented.
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Author Institution: Molecular Spectroscopy Division, National Institute of Standards and Technology