MAGNETIC FIELD EFFECTS ON THE HIGH-RESOLUTION LASER-INDUCED FLUORESCENCE SPECTRA OF THE MOLECULAR EIGENSTATES OF PYRAZINE AND $PYRIMIDINE^{1}$
Loading...
Date
1984
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
Pyrazine (1,4-diazabenzene), when expanded in a seeded and skimmed supersonic jet of argon and crossed with a 200 kHz wide laser beam resonant with the $^{1}B_{3u}\leftarrow ^{1}A_{g}$ electronic transition in the near UV, exhibits a laser-induced fluorescence spectrum which consists of many irregularly spaced rovibronic lines lying under each P- and R-branch $transition.^{2}$ This structure is believed to have its origin in the coupling between a single zero-order singlet level and several nearly isoenergetic levels of a zero-order triplet state. Proof that this is indeed the case has now been provided by studies of the magnetic field dependence of the spectrum, at low fields between 0-100 G, for several different $J^{\prime}$ values. The $J^{\prime}=0$ spectrum exhibits Doppler-broadened lines of width $\sim 10$ MHz, whereas $J^{prime}\neq 0$ spectra show significantly broader lines. An interpretation of these differences in terms of the composition of the molecular eigenstates (ME's), or the ``selection rules for intersystem crossing'', will be given, and the connection between these spectra and the decay properties of coherently prepared $ME's^{3}$ will be established. Similar results for pyrimidine (1,3-diazabenzene), which exhibits qualitatively different behavior in both the frequency and time domains, will be presented.
Description
$^{1}$ Work supported by SON/ZWO, FOM/ZWO, NSF, and NATO. $^{2}$ B.J. van der Meer, et al., Chem Phys. Letters 92, 565 (1982). $^{3}$ Y. Matsumoto, et al., J. Chem. Phys., in press.
Author Institution: Laboratory for Physical Chemistry, R.U. Groningen; Herzberg Institute of Astrophysics, NRC (Canada); Fysisch Laboratorium, K.U. Nijmegen; Department of Chemistry, University of Pittsburgh
Author Institution: Laboratory for Physical Chemistry, R.U. Groningen; Herzberg Institute of Astrophysics, NRC (Canada); Fysisch Laboratorium, K.U. Nijmegen; Department of Chemistry, University of Pittsburgh