Knowledge Bank

While room temperature wavelength resolved emission spectra of the $A~2A2\prime \prime -X~2E1\prime \prime$ transition have existed for nearly 20 $yearsa$, the vibrational assignment of these spectra has remained elusive. The major difficulty with the vibrational analysis is attributable to complications arising from the dynamic Jahn-Teller effect in the $X~$ state. Newly obtained jet-cooled laser excited wavelength resolved fluorescence emmision spectra, in conjunction with $recentb$ calculations aimed at predicting the relevant Jahn-Teller constants have now made the complete analysis of the available spectral data possible. The transitions involving the Jahn-Teller active vibrations have been analyzed in terms of the three lowest energy harmonic vibrations of the appropriate symmetry($e2\prime$), assuming only linear Jahn-Teller interactions. Additional features of the spectrum may be described in terms of the fundamentals, overtones, and combination bands of the non-John-Teller active vibrations as well as combinations involving the Jahn-Teller active modes.