Optical detection of two new isomers of C7H7 in a toluene discharge

Reilly, Neil J.

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https://hdl.handle.net/2142/100756 Copy

Description

Title

Optical detection of two new isomers of C7H7 in a toluene discharge

Author(s)

Reilly, Neil J.

Contributor(s)

• Kokkin, Damian L
• Ross, Sederra D.
• Flores, Jonathan
• Ward, Meredith

Issue Date

2018-06-18

Keyword(s)

Radicals

Abstract

In an effort to optically detect reactive intermediates implicated in mechanisms of C7H7 decomposition and formation, we have been interrogating radical products formed in supersonically cooled discharges of various C7H8 precursors. So far, two C7H7 isomers (neither of which is benzyl or tropyl) have been observed in the 470 − 455 nm region in resonant two-color two-photon ionization spectra. Both isomers were first observed in our laboratory in a toluene discharge, but they can be more efficiently produced from other precursors: one of them, for which we have measured an adiabatic ionization energy (AIE) of 6.92 eV, is highly conspicuous in a discharge of 1,6-heptadiyne; the other, with an AIE of 7.16 eV, is most efficiently generated from cycloheptatriene. Both species possess low frequency vibrational modes suggestive of acyclic structures, and because they absorb at similar wavelengths to the 1-vinylpropargyl radical, may also incorporate substituted propargyl chromophores. Quantum chemical calculations, additional chemical tests, and measurements of ground state vibrational frequencies by dispersed fluorescence are on-going to conclusively assign each spectrum to a particular carrier. The implications of our surprisingly facile discovery of two putatively unknown isomers will be discussed in the context of recent investigations of combustion and pyrolysis processes that begin or terminate with C7H7.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Permalink

http://hdl.handle.net/2142/100756

DOI

10.15278/isms.2018.MJ07

Copyright and License Information

Copyright 2018 Neil J. Reilly

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