Knowledge Bank

The high resolution fluorescence spectrum induced by the 5145 {\AA} line of an argon-ion laser shows complicated features as previously $reported.1$ The $\nu 2$ band has been studied again using a single mode laser and a high resolution spectrograph equipped with an image intersifier. The spectrum was simplified considerably in the single mode excitation. As a result, almost all the spectral lines have been assigned to the direct emission from the initial excited states, in other words, collision induced lines have not been identified even using a wide range of sample pressures. These data give information on some of the ground electronic state constants, $\alpha 2A,\gamma 22A\alpha 2B,x22$ etc. and also enable us to draw an energy level diagram of the excited electronic state. Although strong perturbations are apparent in these $levels2$, this diagram gives an idea of the structure of the excited state. $\mathrm{<mrow\; data-mjx-texclass="ORD">1</mrow>}$ K. Abe, F. Myers, T. K. McCubbin and S. R. Polo, J. Mol. Spectrosc. 38, 552 (1971). $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}$ A. E. Douglas and K. P. Huber, Can. J. Phys. 43, 74 (1965). A. E. Douglas, J. Chem. Phys. 45, 1007 (1966).