Gas phase hyper-Rayleigh scattering measurements.

Measurements of hyper-Rayleigh scattering intensities and polarization ratios are presented for nine small molecules in the gas phase [CH(4), CF(4), CCl(4), N(2)O, NH(3), D(2)O, SO(2), CF(2)Cl(2), and (CH(3))(2)CO]. In four cases [CH(4), CF(4), CCl(4), and N(2)O] all molecular hyperpolarizability tensor components can be determined from the measurements. The results of this experiment are compared with the results of previous ab initio calculations, finding discrepancies up to 60%. Including vibrational contributions decreases the discrepancies for CH(4) and CF(4) and increases them for CCl(4), D(2)O, and NH(3).