EVIDENCE FOR A SECOND LOW LYING n$\Pi^{*}$ SINGLET STATE OF PYRAZINE
Loading...
Date
1973
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
The absorption spectra of pyrazine and some methyl and chloropyrazines have been measured and compared in the region of the ${^{1}} B_{3u} - {^{1}}Ag$, n$\Pi^{*}$ transition of pyrazine. The vapor spectrum of 2, 6-dimethyl pyrazine shows a weak but allowed band system (0,0 at 31 $158 cm^{-1}$) in addition to the stronger, but very broad pyrazine $n\Pi^{*}$ transition ($0, 0 \sim 31 380$ $cm^{-1}$). Rotational contours of the vibronic bands of the weak system and symmetry considerations are consistent with an assignment of this system as the $^{1}B_{2g} (n_-\rightarrow \Pi_{4})$ transition of pyrazine. Vapor absorption spectra, and $4^{\circ} K$ absorption, emission, and excitation spectra of several of the pyrazine derivatives provide additional indirect evidence for an additional low-lying state.
Description
Author Institution: Department of Chemistry, Williams College Williamstown