Spectroscopic Characterization of the First and Second Excited States of the HOSO Radical.
Vincent J EspositoTarek TrabelsiNatasa RohacsJoseph S FranciscoPublished in: The journal of physical chemistry. A (2021)
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 2A and 2 2A electronic states contain minima in their potential energy surfaces. The first excited state 1 2A 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 2A 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 2A (327 nm) and 2 2A (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.