Anisotropic interactions of hydrogen molecules from the pressure dependence of the rotational spectrum in the Ar(H2)(2) compound.

We report the pressure evolution, up to 70 GPa, of the fine structure of the S0(0) rotational excitation in the high-pressure Ar(H(2))(2) compound (with almost 100% para-H(2)) at about 30 K. A perturbative theoretical analysis is developed to calculate intensities and frequency shifts of the active Raman rotational components, on the basis of the intermolecular anisotropic interaction. The comparison between experimental results up to 35 GPa and calculation allows a reliable determination of the anisotropic intermolecular potential in the solid, both for H(2)-H(2) and H(2)-Ar at short range. Such results are important for the interpretation of the high-pressure orientational properties of solid hydrogen.

Collision induced raman scattering as a probe of covalent bonding in mercury diatoms

We show that collision induced Raman spectra of mercury vapors can be understood if a specific contribution to the pair polarizability due to covalent contribution to interatomic interaction is taken into account. Such a result is important because it demonstrates the possibility to use Raman spectroscopy in order to study the nature of the short range interaction in mercury and presumably in all divalent metal pairs.