CS+(B2Σ+−A2Πi) emission produced from dissociative charge-transfer reactions of He+ with CS2 and OCS at thermal energy

Ab initio study of molecular vibrations in the X2Σ+, A2Π, B2Σ+, and C2Σ+ states of CS+ and the vibrational structure in the photoelectron spectrum of CS

“…This x e value agrees well with the previous theoretical values of 907 cm À1 , obtained by the polynomial fitting [11], and 902 cm À1 [13]. The present values differ from the emission spectroscopy values of Tsuji et al [7] by 16 cm À1 for x e and 1.0 cm À1 for x e x e which are within the maximum differences in the X and A states; but they differ from recent emission spectroscopy values [9] by 39 cm À1 for x e and 3.8 cm À1 for x e x e , with significant deviation from the maximum differences. Accordingly, the present x e and x e x e values bear out the experimental values of Tsuji et al as more accurate.…”

“…Fitting of the separation values to a third-order polynomial for DG v 0 þ1=2 in (v 0 + 1/2) by the method of least squares yielded the coefficients (x e , x e x e , x e y e , x e z e ) of the energy expression G(v 0 ). For the X and A states, the theoretical x e and x e x e values agree well within the maximum differences of 21 cm À1 and 1.1 cm À1 , respectively, with the emission and absorption spectroscopy values [6,7,9,10] having better accuracy than the PE spectroscopy values (Table 1).…”

“…1 shows the SOCI potential energy curves (PECs) for the 1-4 2 R + states of CS + and the MRCI PEC for the 1 2 P state. Table 1 lists the theoretical spectroscopic constants for the X1 2 R + , A1 2 P, B2 2 R + , and C3 2 R + states together with experimental values [1,3,4,[6][7][8][9][10]. The theoretical electronic term values (T e ) and equilibrium internuclear distances (R e ) were determined by cubic natural spline (CNS) fitting of the 1-3 2 R + SOCI energies and the 1 2 P MRCI energies.…”

“…(i) The experimental vibrational frequency x e and anharmonicity constant x e x e for the B 2 R + state have not yet been established, because there is a substantial difference between the two sets of x e and x e x e values obtained from emission spectroscopy: 911 cm À1 and 6.5 cm À1 in 1980 [7], and 934.1 cm À1 and 11.3 cm À1 in 1994 [9]. Which values are more accurate?…”

“…These bands have been identified as the transitions from the X 1 R + electronic state of the CS to the X 2 R + , A 2 P, B 2 R + , and C 2 R + states of the CS + [3]. Subsequently, the vibrational levels for the X, A, and B states were studied experimentally, by emission spectroscopy of the A-X [5,6], the B-A [7], and the B-X [8,9] transitions, and by absorption spectroscopy of the A-X transition [10]. No experimental studies other than PE spectroscopy [2][3][4] have yet been reported for the C state.…”