Spectroscopy of Na⁺．Rg and transport coefficients of Na⁺ in Rg(Rg＝He ―Rn)

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Theoretical study of M+ RG2: (M+= Ca, Sr, Ba and Ra; RG= He–Rn)

Ab initio calculations were employed to investigate M+ RG2 species, where M+ = Ca, Sr, Ba and Ra and RG= He–Rn. Geometries have been optimized, and cuts through the potential energy surfaces containing each global minimum have been calculated at the MP2 level of theory, employing triple-ζ quality basis sets. The interaction energies for these complexes were calculated employing the RCCSD(T) level of theory with quadruple-ζ quality basis sets. Trends in binding energies, De, equilibrium bond lengths, Re, and bond angles are discussed and rationalized by analyzing the electronic density. Mulliken, natural population, and atoms-in-molecules (AIM) population analyses are presented. It is found that some of these complexes involving the heavier Group 2 metals are bent whereas others are linear, deviating from observations for the corresponding Be and Mg metal-containing complexes, which have all previously been found to be bent. The results are discussed in terms of orbital hybridization and the different types of interaction present in these species

The (A)over-tilde <-(X)over-tilde(1+1)REMPI spectrum and high-level ab initio calculations of the complex between NO and N-2

The results of two separate studies of the complex between NO and N-2 are reported. The (1+1) REMPI spectrum of the (A) over tilde <--(X) over tilde transition of the complex between NO and N-2 is presented of improved quality over that reported previously, and the appearance of the spectrum is discussed. The results of high-level ab initio calculations [RCCSD(T)/aug-cc-pVQZ//QCISD/6-311+G(2d)] on the (X) over tilde (2)Pi state are also reported. The indications are that the NO moiety is more freely rotating in the complex than is N-2, and that a wide angular space is sampled in the zero-point energy level. The appearance of the REMPI spectrum suggests that the (A) over tilde (2)Sigma (+) state is (close to) linear, and RCCSD(T)//QCISD calculations on the (A) over tilde state, using Rydberg-function-augmented basis sets, suggest that the lowest energy linear isomer is the ON .N-2 linear orientation. It is clear, however, that the understanding of this complex, and its spectroscopy, is far from complete, and will be challenging

Detection by two-photon ionization and magnetic trapping of cold Rb

We present detailed experimental spectra and accurate theoretical interpretation of resonance-enhanced two-photon ionization of ultracold rubidium molecules in the 14000–17000 cm-1 transition energy range. The dimers are formed in a magneto-optical trap by photoassociation followed by radiative decay into the a 3Σu+ lowest triplet state. The theoretical treatment of the process, which reproduces the main features of the spectra, takes into account the photoassociation and decay steps as well as the resonant ionization through the manifold of intermediate gerade states correlated to the 5S + 4D limit. In particular, the energy of the v=1 level of the $(2)\ ^{3}\Sigma_{g}^{+}$ potential well has been determined for the first time. In addition, a tight constraint has been put on the position of the a 3Σu+ repulsive wall. Finally, magnetic trapping of rubidium molecules in the a 3Σu+ state is demonstrated

Theoretical study of Rb2 in He(N): potential energy surface and Monte Carlo simulations.

International audienceAn analytical potential energy surface for a rigid Rb₂ in the ³Σ(u)⁺ state interacting with one helium atom based on accurate ab initio computations is proposed. This 2-dimensional potential is used, together with the pair approximation approach, to investigate Rb₂ attached to small helium clusters He(N) with N = 1-6, 12, and 20 by means of quantum Monte Carlo studies. The limit of large clusters is approximated by a flat helium surface. The relative orientation of the dialkali axis and the helium surface is found to be parallel. Dynamical investigations of the pendular and of the in-plane rotation of the rigid Rb₂ molecule on the surface are presented