Spectroscopic and spin-orbit calculations on the SO+ radical cation

Abstract

Highly correlated ab initio methods were used in order to generate the potential-energy curves of the SO+ electronic states correlating to S+(4Su)+O(3Pg) and S+(2Du)+O(3Pg). These curves were used for deducing accurate spectroscopic properties for these electronic states. Our calculations predict the existence of a 2Phi state lying close in energy to the well-characterized b 4Sigma- state and several weakly bound quartet and doublet states located in the 6-9 eV internal energy range not identified yet. The spin-orbit integrals between these electronic states were evaluated using these highly correlated wave functions, allowing the discussion of the metastability and the predissociation processes forming S+ +O in their electronic ground states. Multistep spin-orbit-induced predissociation pathways are suggested. More specifically, the experimentally determined dissociative potential-energy curve [H. Bissantz et al., Z. Phys. D 22, 727 (1992)] proposed to explain the rapid SO+(b 4Sigma-, v> or =13)-->S+(4Su)+O(3Pg) reaction is found to coincide with the 2 4Pi potential-energy curve for short internuclear distances and with the repulsive 1 6Pi state for longer internuclear separations.

Ab initio characterization of electronically excited metastable states of S2 -

“…and 440 cm −1 [25]. The differences are within our estimation of ∼5% accuracy for this property [1,[25][26][27]. This agreement suggests that the experimentally unknown spin-orbit constants for the S 2 − electronic states should be of similar accuracy.…”

“…The agreement for the neutral spectroscopic parameters and with previous works for S 2 − makes possible reliable predictions for the unknown anionic states. Indeed, for S 2 (X 3 g − ) our MRCI + Q internuclear distance of 1.898Å differs by less than 0.01Å from both the experimental (1.889Å [26]) and earlier MRCI + Q (1.907Å [14]) values, and the harmonic wavenumber (716.8 cm −1 ) compares rather well with the values (725.65 cm −1 and 734 cm −1 ) given in [26] and [14], respectively. For S 2 − (X 2 g ), there is also a good agreement between our R e value (2.021Å) and previous experimental (2.005 ± 0.015Å [5]) and theoretical (2.018Å [14]) determinations.…”

Mid-infrared diode laser spectroscopy of SO+

“…The change of the sign of c eff probably indicates a substantial change of A D for the t = 1 state. The internuclear distance dependence of the spin-orbit coupling constant for the X 2 P r state of SO + was first calculated by Cossart et al [13], and later by Houria et al [9] with highly correlated ab initio methods. Both calculations indicate that the r (S-O distance) dependence of the spin-orbit coupling constant is not monotonous around the equilibrium internuclear dis- tance r e , suggesting that A D for the t = 1 state can be significantly different from that for the t = 0 state.…”

“…For a brief review of previous experimental and theoretical studies on SO + , see Ref. [9] and references therein. In 1974, a potential energy diagram for SO + was constructed by Dyke et al based on the photoelectron spectroscopic data of SO radicals [10].…”

“…Ornellas et al [19] reported a theoretical characterization of quartet states of SO + using the internally contracted multi-reference configuration interaction approach and natural orbits. Recently, Houria et al [9] carried out a spectroscopic and spin-orbit calculations on SO + using highly correlated ab initio methods.…”