Ab initiostudy of the KrH+ photodissociation

Quantum computations in heavy noble-gas hydride cations: Reference energies and new spectroscopic data

Computational quantum chemistry has become a powerful tool with a wide range of possibilities to solve chemical-physical problems. As a result of this, the interest in the applications of computational quantum chemistry has expanded considerably, and has opened up novel research opportunities. In particular, those related to the characterization of heavy-atoms complexes, as most electronic structure calculations for such systems struggle with the problem posed by the large number of electrons present in them, and consequently, the introduction of relativistic effects. The present study performed an exhaustive assess to characterized the uncommon NgH+ (Ng = Kr, Xe, and Rn) hydride cations in order to provide accurate rovibrational data of their isotopes to assist in the laboratory characterization or even their astronomical detection. Scalar relativistic effects were included, and the ground and first electronically exited states potential curves were obtained from benchmark ab initio CCSD(T)/CBS and MRCI+Q electronic structure calculations. Next, such interaction potentials, correctly extended to long-range asymptotic regions, were employed in quantum bound state calculations and molecular spectroscopic constants were determined for the most abundance 84Kr, 132Xe, and 222Rn isotopes. Our results were discussed in comparison with available experimental and previous theoretical estimates, aiming to treat accuracy issues. The new sets provide reference data that could serve for spectroscopic characterization of such low abundance and high radioactive species.

Spin-orbit configuration interaction study of the ultraviolet photofragmentation of XeH+

The multireference spin-orbit CI method is employed to calculate potential energy curves for the ground and low-lying excited states of the XeH+ cation. For the first time, the spin-orbit interaction is taken into account and electric dipole moments are computed for transitions to the states responsible for the first absorption continuum (A band) of XeH+. On this basis, the partial and total absorption spectra in this energy range are obtained. It is found that the A-band absorption is dominated by the spin-forbidden b3Pi0+ <-- X1sigma+ parallel transition, while perpendicular transitions to the B(1)Pi and b(3)Pi(1) states are significantly weaker. The Gamma(nu) branching ratio defined as the ratio of the Xe+(2P(1/2)) yield to the total yield of the Xe+ cations from the XeH+ photodissociation is calculated for the (42-80) x 10(3) spectral range. It is shown that Gamma(nu) increases smoothly from <0.2 in the red and blue tails of the band to its maximum of 0.92 in the middle of the band, at E approximately 51.4 x 10(3) cm(-1). The high Gamma(nu) values correspond to the predominant formation of the spin-excited Xe+(2P(1/2)) ions that may be used to obtain IR laser generation at the Xe+(2P(1/2) - 2P(3/2)) transition. The calculated XeH+ data are compared with those for the isovalent ArH+, KrH+, and HI systems.