Photoionization of Propargyl and Bromopropargyl Radicals: A Threshold Photoelectron Spectroscopic Study

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• 作者：Patrick Hemberger ; Melanie Lang ; Bastian Noller ; Ingo Fischer ; Christian Alcaraz ; Ba虂rbara K. Cunha de Miranda ; Gustavo A. Garcia ; He虂loi虉se Soldi-Lose
• 刊名：Journal of Physical Chemistry A
• 出版年：2011
• 出版时间：March 24, 2011
• 年：2011
• 卷：115
• 期：11
• 页码：2225-2230
• 全文大小：866K
• 年卷期：v.115,no.11(March 24, 2011)
• ISSN：1520-5215

文摘

In this Article, we present mass-selected threshold photoelectron spectra of propargyl as well as the 1- and 3-bromopropargyl radicals. The reactive intermediates were produced by flash pyrolysis of suitable precursors and ionized by VUV synchrotron radiation. The TPES of the propargyl radical was simulated using data from a recent high-level computational study. An ionization energy (IE) of 8.71 卤 0.02 eV was obtained, in excellent agreement with computations, but slightly above previous experimental IEs. The pyrolysis of 1,3-dibromopropyne delivers both 1- and 3-bromopropargyl radicals that can be distinguished by their different ionization energies (8.34 and 8.16 eV). To explain the vibrational structure, a Franck鈭扖ondon simulation was performed, based on DFT calculations, which can account for all major spectral features. Bromopropargyl photoionizes dissociatively beginning at around 10.1 eV. Cationic excited states of 1- and 3-bromopropargyl were tentatively identified. The dissociative photoionization of the precursor (1,3-dibromopropyne) was also examined, delivering an AE_0K (C₃H₂Br⁺/C₃H₂Br₂) of 10.6 eV.