Probing the Dipole-Bound State of the Cryogenically Cooled 2-Chlorothiophenoxide Anion via Photoelectron Imaging and Photodetachment Spectroscopy.

Chlorothiophenols are key precursors for polychlorinated dibenzothiophenes, which are a class of persistent organic pollutants environmentally, but little is known about their electronic and spectroscopic properties. We report a high-resolution spectroscopic investigation of the cryogenically cooled 2-chlorothiophenoxide (2-CTP) anion using photoelectron imaging, photodetachment spectroscopy, and resonant photoelectron spectroscopy. High-resolution photoelectron spectroscopy yields an accurate electron affinity of 21,005 ± 5 cm (2.6043 ± 0.0006 eV) for the 2-chlorothiophenoxy radical as well as an excited electronic state at 0.295 eV above the ground state. Photodetachment spectroscopy reveals a dipole-bound state (DBS) for the 2-CTP anion at 113 cm below the detachment threshold and 14 vibrational Feshbach resonances. Resonant photoelectron spectra via vibrational autodetachment are obtained, resulting in rich spectroscopic information about the ground state of the 2-CTP radical. A resonant two-photon detachment experiment via the zero-point level of the DBS indicates relaxation from the DBS to a lower-lying excited state of the 2-CTP anion as well as low-lying vibrational levels of the anion ground state. The current study yields a wealth of spectroscopic information for the 2-CTP radical and the 2-CTP anion, which is valuable for understanding the energetics and reactivities of these environmentally important species.