Laser fluorescence excitation spectroscopy of the CAr van der Waals complex

Interactions of Si+(2PJ) and Ge+ (2PJ) with rare gas atoms (He-Rn): interaction potentials, spectroscopy, and ion transport coefficients

Accurate interatomic potentials were calculated for the interaction of a singly-charged silicon cation, Si⁺, with a single rare gas atom, RG (RG = Kr-Rn), as well as a singly-charged germanium cation, Ge⁺, with a single rare gas atom, RG (RG = He-Rn). The RCCSD(T) method and basis sets of quadruple-ζ and quintuple-ζ quality were employed; each interaction energy is counterpoise corrected and extrapolated to the basis set limit. The lowest electronic term (²P) of each cation was considered, and the interatomic potentials calculated for the diatomic terms that arise from these: ²Π and ²Σ⁺. Additionally, the interatomic potentials for the respective spin-orbit levels were calculated, and the effect on the spectroscopic parameters was examined. Variations in several spectroscopic parameters with the increasing atomic number of RG were examined. The presence of incipient chemical interaction was also examined via Birge-Sponer-like plots and various population analyses across the series. In the cases of heavier RG, these were consistent with a small amount of electron transfer from the heavier RG atom to the cation, rationalizing the spin-orbit splittings. This was also supported by the observed larger-than-expected spin-orbit splittings for the Si⁺-RG complexes. Finally, each set of RCCSD(T) potentials including spin-orbit coupling was employed to calculate transport coefficients for the cation moving through a bath of the RG. The calculated ion mobilities showed significant differences for the two atomic spin-orbit states, arising from subtle changes in the interaction potentials.

Spectroscopic investigation of nonbonding interactions of group-14 atoms with rare gases: the SnAr van der Waals complex

The laser fluorescence excitation spectra of the SnAr van der Waals complex, in the vicinity of the individual fine-structure lines of the Sn 5s25p6s3P0<-- 5s25p2(3)P atomic resonance transition in the spectral region 317-270 nm are reported. Excited-state (v',0) progressions of bands built upon the individual J'<-- J" fine-structure atomic lines were observed. Because the collisional spin-orbit relaxation was slow, transitions were observed out of the lower SnAr states built upon all the J'' atomic asymptotes. The spectra were interpreted through model potential energy curves based on the isoelectronic SiAr system. Lower bounds to the dissociation energies of all lower SnAr states were determined. The binding energies of the group-13, and -14-atom-argon complexes and the effect of the spin-orbit interaction on moderating nonbonding interactions are discussed.