Induced anisotropy of Ar2: A state-of-the-art semiempirical model

Heavy rare-gas atomic pairs and the "double penalty" issue: Isotropic Raman lineshapes by Kr2, Xe2, and KrXe at room temperature

We report absolutely calibrated isotropic Raman lineshapes for Kr2 and Xe2 and for KrXe at 294.5 K and compare them to quantum-mechanically generated lineshapes by using state-of-the-art second-order Møller-Plesset and DFT/B3LYP data sets for the induced mean dipole polarizability ᾱ. A very good agreement between the numerical and the experimental data was observed but the large uncertainty margins and the short Raman frequency interval probed in our experiment prevented us from rating on a more refined scale the performance of the tested ᾱ models. These drawbacks are inherent in isotropic Raman spectrum measurements and amplified for dissimilar pairs because, for such systems and spectra, the unreliable operation of subtracting optical signals of comparable magnitude occurs twice per Raman frequency shift value, thus penalizing twice the quality of the measured data. In light of our findings and of previously reported evidence about related electric properties in Kr2 and Xe2 and in KrXe, we are left with no doubt as to the consistency of the induced-polarizability and interatomic-potential data used for these three systems at the reported level of accuracy.

Experimental and theoretical determination of the dipole-quadrupole and dipole-octopole polarizabilities of the group IV tetrachlorides TiCl4, ZrCl4, and HfCl4

The dipole-quadrupole and dipole-octopole polarizabilities A and E of TiCl4, ZrCl4, and HfCl4 have been determined from collision-induced light-scattering experiments. Our respective experimental results for /A/ are (165+/-10), (110+/-30), and (140+/-20) e2a0 3Eh (-1), whereas /E/ is determined to be (675+/-125), (750+/-200), and (670+/-400) e2a0 4Eh (-1). Theory predicts values convincingly close to experiment, as A=(181.4+/-9.1), (167.6+/-8.4), and (139.8+/-7.0) e2a0 3Eh (-1), and E=(-671+/-67), (-688+/-69), and (-574+/-57) e2a0 4Eh (-1). In addition our quantum chemical ab initio calculations give reliable values for the dipole polarizability alpha, as well as for the octopole and hexadecapole moments Omega and Phi for all three substances.