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

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^-1 (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^-1 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.