Spectroscopic observation of the resonance-stabilized 1-phenylpropargyl radical

J Am Chem Soc. 2008 Mar 12;130(10):3137-42. doi: 10.1021/ja078342t. Epub 2008 Feb 15.

Abstract

The gas-phase laser-induced fluorescence (LIF) spectrum of a 1-phenylpropargyl radical has been identified in the region 20,800-22,000 cm(-1) in a free jet. The radical was produced from discharges of hydrocarbons including benzene. Disregarding C2, C3, and CH, this radical appears as the most strongly fluorescing product in a visible wavelength two-dimensional fluorescence excitation-emission spectrum of a jet-cooled benzene discharge. The structure of the carrier was elucidated by measurement of a matching resonant two-color two-photon ionization spectrum at m/z = 115 and density functional theory. The assignment was proven conclusively by observation of the same excitation spectrum from a low-current discharge of 3-phenyl-1-propyne. The apparent great abundance of the 1-phenylpropargyl radical in discharges of benzene and, more importantly, 1-hexyne may further underpin the proposed importance of the propargyl radical in the formation of complex hydrocarbons in combustion and circumstellar environments.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alkynes / chemistry*
  • Free Radicals / chemistry
  • Lasers*
  • Models, Chemical
  • Molecular Structure
  • Sensitivity and Specificity
  • Spectrometry, Fluorescence / methods

Substances

  • Alkynes
  • Free Radicals