Knowledge Bank

When $CS2$ is excited in the 280 - 340 nm region, its dispersed fluorescence displays both discrete and continuum-like components. Our bulb studies have shown that the continuum is enhanced by collisions, but persists in the low pressure limit where collisions during the excited state lifetime are unlikely. This work in a supersonic jet confirms that continuum emission persists under essentially collision-free conditions. The continuum emission is identified both by dispersing the fluorescence and by observing its long (relative to the discrete emission) lifetime. The amount of continuum compared to discrete emission is monitored as the excitation wavelength is scanned through the region of the T and V systems bands. Continuum emission is excited almost everywhere; an apparent continuum in excitation corresponds to the one seen in emission. In the region of excitation bands the discrete and continuum emissions do not track each other; the continuum/discrete ratio varies with J. The origin of $CS2$ continuum-like emission is discussed using a model proposed by $Hardwick1$ to explain similar emission for $NO2$.