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Updated: Jan 3, 2026

Photoelectron Imaging of Anions Illustrated by 310 Nm Detachment of F−
Published on: July 27, 2018
The absolute photoionization cross section of the mercapto radical (SH) from threshold up to 15.0 eV
Helgi Rafn Hrodmarsson1, Gustavo A Garcia, Laurent Nahon
1Synchrotron SOLEIL, L'Orme des Merisiers, St Aubin, BP 48, Gif sur Yvette, France. hrodmarsson@strw.leidenuniv.nl hr.hrodmarsson@gmail.com.
Abstract:
We present the absolute photoionization cross-section of the mercapto radical, SH, recorded from its first ionization energy at 10.4 eV up to a photon energy of 15 eV. The absolute scale was calibrated at the fixed photon energy of 11.2 eV using the known values of H2S and S as references. SH and S were produced in a microwave discharge flow-tube reactor by hydrogen abstraction of the H2S precursor. The measured photoionization cross-section of SH dramatically differs from the one currently employed to model the presence of this species in a number of astronomical environments, where SH along with its ionic counterpart SH+ have been detected. The cation spectroscopy and fragmentation of H2S, SH and S in the 9.2-15.0 eV energy range obtained using threshold photoelectron techniques is also presented and discussed in the context of existing literature.
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