VIBRATIONAL-TORSIONAL COUPLING REVEALED IN THE INFRARED SPECTRUM OF HE-SOLVATED n-PROPYL RADICAL

Moradi, Christopher P.

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https://hdl.handle.net/2142/79226 Copy

Description

Title

VIBRATIONAL-TORSIONAL COUPLING REVEALED IN THE INFRARED SPECTRUM OF HE-SOLVATED n-PROPYL RADICAL

Author(s)

Moradi, Christopher P.

Contributor(s)

• Douberly, Gary E.
• Schaefer III., Henry F.
• Agarwal, Jay
• Broderick, Bernadette M.

Issue Date

23-Jun-15

Keyword(s)

Radicals

Abstract

The textit{n}-propyl and textit{i}-propyl radicals were generated in the gas phase via pyrolysis of textit{n}-butyl nitrite (CH$_{3}$(CH$_{2}$)$_{3}$ONO) and textit{i}-butyl nitrite (CH$_{3}$CH(CH$_{3}$)CH$_{2}$ONO) precursors, respectively. Nascent radicals were promptly solvated by a beam of He nanodroplets, and the infrared spectra of the radicals were recorded in the C-H stretching region. In addition to three vibrations of textit{n}-propyl previously measured in an Ar matrix,footnote{Pacansky, et. al., J. Phys. Chem. 1977, 81, 2149.} we observe many unreported bands between 2800 and 3150 $wn$, which we attribute to propyl radicals. The C-H stretching modes observed above 2960 $wn$ for both radicals are in excellent agreement with anharmonic frequencies computed using VPT2. Between 2800 and 2960 $wn$, however, the spectra of textit{n}-propyl and textit{i}-propyl radicals become quite congested and difficult to assign due to the presence of multiple anharmonic resonances. Computations reveal the likely origin of the spectral congestion to be strong coupling between the high frequency C-H stretching modes and a lower frequency torsional motion, which modulates quite substantially a through-space hyperconjugation interaction.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

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http://hdl.handle.net/2142/79226

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