Low-energy photoelectron imaging of HS2 anion

Abstract

Low-energy photoelectron imaging of HS2 (-) has been investigated, which provides the vibrational frequencies of the ground state as well as the first excited state of HS2. It allows us to determine more accurate electron affinity of HS2, 1.9080 ± 0.0018 eV. Combined with Frank-Condon simulation, the vibrational features have been unveiled related to S-S stretching and S-S-H bending modes for the ground state and S-S stretching, S-S-H bending, and S-H stretching modes for the first excited state. Photoelectron angular distributions are mainly characteristic of electron detachment from two different molecular orbitals (MOs) in HS2 (-). With the aid of accurate electron affinity value of HS2, corresponding thermochemical quantities can be accessed.

Accurate double many-body expansion potential energy surface of HS 2 A 2 A′) by scaling the external correlation

“…Since the DMBE-SEC method is employed to model the ab initio energies, the well depth of the global minimum is 0.0078E h lower than that of MRCI(Q)/AVQZ. As for the harmonic frequencies, the DMBE/SEC PES from the present work predicts values of 2714.19 cm −1 , 504.45 cm −1 , and 812.27 cm −1 , which are in good agreement with the most recent experimental values given by Qin et al, [7] which are 2585 ± 81 cm −1 , 490 ± 41 cm −1 , and 741 ± 41 cm −1 , respectively. The contour maps for the H( 2 S) + S 2 (a 1 ∆ g ) → SH(X 2 Π) + S( 3 P) reaction in internal coordinates at four H-S-S angles (∠HSS = 0 • , 45 .…”

“…Exp. [7] - present DMBE/SEC PES locates at R 1 = 3.937a 0 , R 2 = 2.540a 0 , and R 3 = 4.836a 0 (R 1 is the SS interatomic separation, while R 2 and R 3 are the two SH interatomic separations), differing only 0.025a 0 , 0.002a 0 , and 0.003a 0 from the MRCI(Q)/AVQZ results, respectively. Compared with the theoretical works of Peterson et al [17] and Denis, [16] the maximal differences occur in R 3 , which are only 0.043a 0 and 0.025a 0 , respectively.…”

“…Sulfur-containing species have received growing attention due to their important role played in the air pollution and acid rain. [1][2][3][4][5][6][7] Among various sulfur-containing compounds, the HS 2 radical is one of the most important species, which is responsible for the oxidation of reduced forms of sulfur, the reaction in combustion [8][9][10] and biochemistry. [11,12] Therefore, extensive studies on the HS 2 radical have been carried out both theoretically and experimentally for decades.…”

“…Song et al [18] reported an accurate double many-body expansion (DMBE) potential energy surface (PES) for ground-state HS 2 based on ab initio energies extrapolated to the complete basis set limit. Quite recently, Qin et al [7] calculated the equilibrium geometry of the first excited electronic state of HS 2 by time-dependent density functional theory using the hybrid functional B3LYP with the aug-cc-pVQZ (AVQZ) basis set.…”

Interaction and Photodissociation of Electronic Excited States of HS2 in the Ultraviolet Region: A Theoretical Contribution

“…More accurate information about the ground-state X 2 A″ has been determined experimentally by millimeter spectrum, microwave spectrum, and infrared spectrum . The A 2 A′ ← X 2 A″ transition has been recently re-investigated by several advanced techniques including high-resolution Fourier transform, photodetachment-photoelectron spectroscopy, and low-energy photoelectron imaging, from which the geometries and spectroscopic constants of both states have been obtained. Theoretically, X 2 A″ and A 2 A′ states have been extensively studied using various methods, such as self-consistent field (SCF), configuration interaction (CI), coupled-cluster singles and doubles model (CCSD), coupled cluster singles and doubles with perturbative triples (CCSD­(T)), − and B3LYP methods.…”