Knowledge Bank

High-resolution stimulated Raman spectroscopy has been used to observe optical Stark effects in rotational-vibrational transitions in molecular oxygen. Broadening, shifting, and/or splitting of individual Raman lines results from the inhomogeneous optical fields of the intense pump laser. An analysis of the position of a number of normal and satellite lines in both the polarized and depolarized spectra has led to a measurement of a value for the excited state polarizability anisotropy, $\gamma 1=(1.36\pm 0.17)\times 10-24cm3$, and to a more accurate value for the band origin, $\nu 0=1556.385\pm 0.001cm-1$. This experimentally determined value of $\gamma 1$ represents the first spectroscopic measurement of an excited state polarizability anisotropy.