Spectroscopic Characterization of the First and Second Excited States of the HOSO Radical

Abstract

The spectroscopic properties of the ground and first two excited states of the HOSO radical are investigated using the internally contracted multireference configuration interaction method, including the Davidson correction (MRCI+Q) and explicit treatment of the electron correlation (MRCI-F12). The vertical and adiabatic excitation energies are also determined. The results reveal that both the 1 2 A and 2 2 A electronic states contain minima in their potential energy surfaces. The first excited state 1 2 A possesses a nonplanar structure and has an adiabatic excitation energy of 1.45 eV (855 nm), lying in the near-infrared region. The second excited state 2 2 A has a planar geometry and an adiabatic excitation energy of 2.91 eV (426 nm) existing in the visible region. The calculated oscillator strengths for the vertical electronic excitations to the 1 2 A (327 nm) and 2 2 A (270 nm) states are 0.003 and 0.022, respectively, indicating experimental intensity should be observed. The small but non-negligible Franck− Condon factors for excitations ∼300 nm, and the broad and intense absorption feature in the 225−275 nm region suggest that detection of the HOSO radical with electronic spectroscopy may be feasible.

Spectroscopic Characterization of HSO2• and HOSO• Intermediates Involved in SO2 Geoengineering

“…The first, ranging from 200 to 250 nm is attributed to the D 2 A ← X 2 A excitation, while the second at 160–200 nm contains two almost identical shapes corresponding to the E 2 A ← X 2 A and F 2 A ← X 2 A excitations. The two broad bands in the spectrum have a maximum calculated absorption cross section of ∼3.25 × 10 –18 cm 2 molecule –1 , approximately half the strength of the isomeric species HOSO • (∼5.5 × 10 –18 cm 2 molecule –1 ) and an order of magnitude greater than that of SO 2 (∼10 –19 cm 2 molecule –1 ) at 248 nm …”

“…Meanwhile, the peak in the 160−250 nm range consists of two overlapping absorption features. The first, ranging from 200 to 250 nm is attributed to the D 2 A ← X 2 A excitation, while the 38 and an order of magnitude greater than that of SO 2 (∼10 −19 cm 2 molecule −1 ) at 248 nm. 39 Experimentally, HSO 2…”

Vibrational, Rotational, and Electronic Spectroscopy for Possible Interstellar Detection of AlNH2 and HAlNH

“…The internal sum in Equation (A1) runs over the total number of Wigner geometries, while the external sum includes transitions from the initial state i to the final states j, and δ is a broadening factor arbitrarily set to 0.1 eV. Further details can be found in Karsili et al (2018), Esposito et al (2021), and Friskey et al (2022.…”

Reactivity properties of the HOSO and HSO2 isomers in liquid medium: a sequential Monte Carlo/quantum mechanics study

“…In turn, SO 2 under the effect of solar radiation reacts with H 2 O producing the radicals OH and HOSO [4], precursors to H 2 SO 4 [3]. Previous works have been devoted to the study of the electronic ground [5][6][7][8] and excited states [9,10] of the HSO 2 molecular system, while chemical reactions in the gas phase involving such species have been theoretically studied in the frame of quasi-classical trajectories [10][11][12][13][14]. Some of the calculated reaction rate constants were used in kinetic models at the low and high-temperature limits [15,16].…”