On the absolute photoionization cross section and dissociative photoionization of cyclopropenylidene. Issue 13 (15th March 2016)

• Record Type: Journal Article
• Authors: Holzmeier, Fabian; Fischer, Ingo; Kiendl, Benjamin; Krueger, Anke; Bodi, Andras; Hemberger, Patrick
• Is Part Of: Physical chemistry chemical physics. Volume 18:Issue 13(2016)
• Page Start: 9240
• Page End: 9247
• Publication Date: 2016-03-15
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c6cp01068g
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : We report the determination of the absolute photoionization cross section of cyclopropenylidene, c -C3 H2, and the heat of formation of the C3 H radical and ion derived by the dissociative ionization of the carbene. Abstract : We report the determination of the absolute photoionization cross section of cyclopropenylidene, c -C3 H2, and the heat of formation of the C3 H radical and ion derived by the dissociative ionization of the carbene. Vacuum ultraviolet (VUV) synchrotron radiation as provided by the Swiss Light Source and imaging photoelectron photoion coincidence (iPEPICO) were employed. Cyclopropenylidene was generated by pyrolysis of a quadricyclane precursor in a 1 : 1 ratio with benzene, which enabled us to derive the carbene's near threshold absolute photoionization cross section from the photoionization yield of the two pyrolysis products and the known cross section of benzene. The cross section at 9.5 eV, for example, was determined to be 4.5 ± 1.4 Mb. Upon dissociative ionization the carbene decomposes by hydrogen atom loss to the linear isomer of C3 H + . The appearance energy for this process was determined to be AE0K ( c -C3 H2 ; l -C3 H + ) = 13.67 ± 0.10 eV. The heat of formation of neutral and cationic C3 H was derived from this value via a thermochemical cycle as Δf H 0K (C3 H) = 725 ± 25 kJ mol −1 and Δf H 0K (C3 H + ) = 1604 ± 19 kJ mol −1, using a previously reported ionization energy of C3 H.