Interacting He and Ar atoms: Revised theoretical interaction potential, dipole moment, and collision-induced absorption spectra.

Coupled cluster quantum chemical calculations of the potential energy surface and the induced dipole surface are reported for the He-Ar van der Waals collisional complex. Spectroscopic parameters are derived from global analytical fits while an accurate value for the long-range dipole coefficient D7 is obtained by perturbation methods. Collision-induced absorption spectra are computed quantum mechanically and compared with existing measurements.

Infrared absorption by collisional H2-He complexes at temperatures up to 9000 K and frequencies from 0 to 20,000 cm(-1).

Quantum chemical methods have been used elsewhere to obtain the potential energy surface (PES) and the induced dipole surface (IDS) of H(2)-He collisional complexes at eight different H-H bond distances, fifteen atom-molecule separations, and 19 angular orientations each [X. Li, A. Mandal, E.

Collision-induced absorption by H2 pairs: from hundreds to thousands of kelvin.

An interaction-induced dipole surface (IDS) and a potential energy surface (PES) of collisionally interacting molecular hydrogen pairs H(2)-H(2) was recently obtained using quantum chemical methods (Li, X.; et al. Computational Methods in Science and Engineering, ICCMSE.

Collision-induced absorption at wavelengths near 5 microm by dense hydrogen gas.

Based on a recent ab initio interaction-induced dipole surface of collisionally interacting molecular hydrogen pairs H(2)-H(2), we compute the binary absorption coefficients at wavelengths near 5 microm at temperatures of 77.5 and 297 K for comparison with existing laboratory measurements. We observe satisfactory agreement of the measurements with our calculations, thereby concluding an earlier study [Gustafsson et al.

Roto-translational Raman spectra of pairs of hydrogen molecules from first principles.

We calculate the collision-induced, roto-translational, polarized, and depolarized Raman spectra of pairs of H(2) molecules. The Schrodinger equation of H(2)-H(2) scattering in the presence of a weak radiation field is integrated in the close-coupled scheme. This permits the accounting for the anisotropy of the intermolecular potential energy surface and thereby it includes mixing of polarizability components.

Infrared absorption by collisional CH4+X pairs, with X=He, H2, or N2.

Existing measurements of the collision-induced rototranslational absorption spectra of gaseous mixtures of methane with helium, hydrogen, or nitrogen are compared to theoretical calculations, based on refined multipole-induced and dispersion force-induced dipole moments of the interacting molecular pairs CH4-He, CH4-H2, and CH4-N2. In each case the measured absorption exceeds the calculations substantially at most frequencies. We present the excess absorption spectra, that is the difference of the measured and the calculated profiles, of these supramolecular CH4-X systems at various gas temperatures.

Far-infrared absorption by collisionally interacting nitrogen and methane molecules.

Quantum line shape calculations of the rototranslational enhancement spectra of nitrogen-methane gaseous mixtures are reported. The calculations are based on a recent theoretical dipole function for interacting N(2) and CH(4) molecules, which accounts for the long-range induction mechanisms: multipolar inductions and dispersion force-induced dipoles. Multipolar induction alone was often found to approximate the actual dipole surfaces of pairs of interacting linear molecules reasonably well.

Electron-ion bremsstrahlung spectra calculations for sonoluminescence.

The bremsstrahlung spectra arising from electron-ion collisions are calculated for temperatures from 5000 K to 40 000 K and wavelengths from 100 nm to 1000 nm, for the ions He+, Ne+, Ar+, Kr+, Xe+, H+, and O+, using Hartree-Fock-Slater potentials. The spectral intensities are expressed in terms of Gaunt factors, the ratios of the present quantum computation and existing semiclassical results. For the heavy rare gas ions Gaunt factors of up to 3 are obtained at wavelengths of 200 nm.

Microwave emission of sonoluminescing bubbles.

Kordomenos et al. have attempted to measure single bubble sonoluminescence (SBSL) emission in the microwave window of water in a band of frequencies ranging from 1.65 GHz to 2.

Light emission of sonoluminescent bubbles containing a rare gas and water vapor.

We present numerical simulations of sonoluminescent rare-gas bubbles in water, which account for (i) time variations of the water vapor content, (ii) chemical reactions, and (iii) the ionization of the rare gas and the H2O dissociation products. Peak temperatures exceed 10 000 K at densities of a few hundred amagat ( approximately 10(28) particles per m(3)). The gas mixture in the bubble is weakly ionized.