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

Abstract

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 parallel transition, while perpendicular transitions to the B¹Π and b³Π₁ states are significantly weaker. The Γ(ν) 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) × 10³ spectral range. It is shown that Γ(ν) 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 ≃ 51.4 × 10³ cm⁻¹. The high Γ(ν) 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.