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Updated: May 29, 2026

Photogeneration of N-Heterocyclic Carbenes: Application in Photoinduced Ring-Opening Metathesis Polymerization
Published on: November 29, 2018
Positive and negative photoion spectroscopy study of monochlorothiophenes
Yun-Feng Xu1, Shan Xi Tian, Liuli Chen
1Hefei National Laboratory for Physical Sciences at the Microscale and Department of Chemical Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
Abstract:
Photolysis dynamics of monochlorothiophenes (2- and 3-chlorothiophenes) is investigated using positive and negative photoion mass spectrometry combined with the synchrotron vacuum ultraviolet radiation. A dozen of the daughter cations are observed in the time-of-flight mass spectra, and their appearance energies are determined by the photoion efficiency spectroscopy measurements. At the energetic threshold, the concerted process rather than a stepwise reaction for C(4)H(3)SCl(+) → C(2)HSCl(+) + C(2)H(2) and the ring-open isomers of the dehydrogenated thiophene cations (C(4)H(3)S(+) and C(4)H(2)S(+)) formed in C(4)H(3)SCl(+) → C(4)H(3)S(+) + Cl and C(4)H(2)S(+) + HCl are proposed on the basis of the B3LYP/6-311+G(3df,3pd) calculations. The chlorine anion (Cl(-)) is observed as the product of the photoion-pair dissociations in the energy range of 10.70-22.00 eV. A set of valence-to-Rydberg state transitions 12a' → np (n = 6, 7, 8, 9, 10, etc.) and several series of vibrational excitations are tentatively assigned in the Cl(-) spectrum of 2-chlorothiophene in the lower energy range of 10.90-12.00 eV.
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