Measurement of the Raman polarizability anisotropy for the v = 1 pure rotational Raman transition in H 2 by rotational Raman spectroscopy

A combination of stimulated Raman pumping and rotational Raman spectroscopy is used to accomplish the first measurement of the polarizability anisotropy γ11,13 (355 nm) for the S11 (1) transition in molecular hydrogen H2. Saturation of the Q01(1) transition connecting the |X1 Σ+ g, v = 0, J = 1 > state to the |X1 Σ+ g, v = 1, J = 1 > state in H2 by stimulated Raman pumping is the critical element in this experiment. The observed intensities of the rotational Raman lines for these states allow an estimate of γ11,13 (355 nm) as 0.358 ± 0.004 A3. A comparison of this value to that obtained from fundamental ab initio calculations in H2 also is possible for the first time.