Knowledge Bank

The present experiments on Lyman and Werner bands of HD and $D2$ in Ar follow similar experiments with $H2$ in Ar and Kr. The Kr discharge produces no appreciable enhancements in HD and $D2$, although it does so in $H2$. Additional support is given to accepted processes for selective enhancement, namely, resonance fluorescence and collisions of the second kind involving allowed levels. Again, no enhancement effect by metastable levels was detected. Further experiments with a light source separated from the target molecules have not yet been carried out. Higher vibrational levels than have been reported until now were observed in the ground states of HD and $D2$, up to $v=15$ and 20, respectively. The level $v=20$ is found to be the highest vibrational level in the ground state of $D2$. Although this value is not yet known in HD directly, the figure $v=17$ is indicated by $\Delta G$ extrapolation.