Dye-laser intracavity absorption spectrum of the hydrogen molecule

Dye-laser intracavity absorption (ICA) has been used to study the molecular spectrum of H2 excited by a microwave discharge in the wavelength region between 5680 and 6204 A. Transitions from the non-predissociated 2c3II/sub u/ state are prominent in the spectrum, and also transitions from the 2a3Σ/sub g/+ state to higher states appear strongly. In addition, some transitions from the predissociated 2c3II/sub u/ state to excited states are also observed. The lifetimes of the 2a3Σ/sub g/+ and predissociated 2c3II/sub u/ states, which are of the order of 10-8 and 10-9 seconds, respectively, are very short compared to that of the metastable 2c3II/sub u/ states (10-3 sec). This shows that ICA is very sensitive and allows the observation of transitions from short-lived states. Also, from this experiment, it turns out that ICA might be a useful tool to study physical processes such as collision and energy distribution, in excited molecules