Vibrationally selective radiative and non-radiative transitions in gaseous hydrogen molecules.

An efficient vibrationally selective technique to build-up the v″=1 vibrational levels in gaseous hydrogen is demonstrated using stimulated Raman pumping (SRP). Both photo-acoustic Raman spectroscopy (PARS) and coherent anti-Stokes Raman spectroscopy (CARS) are used to study non-radiative and radiative (v″=0 and v″=1) transitions in gaseous H(2) molecules. The population fraction in the v″=1 vibrational level has been estimated using combined photo-acoustic and coherent anti-Stokes Raman spectroscopy with stimulated Raman pumping.