The intramolecular vibrational energy redistribution threshold in S(1) deuterated p-difluorobenzene.
The intramolecular vibrational energy redistribution (IVR) in S(1) deuterated p-difluorobenzene (pDFB-d(4) or -d(4)) has been studied to determine the IVR threshold. For this, the S(1) <-- S(0) fluorescence excitation (FE) spectrum of jet-cooled d(4) was investigated in the 2000-3250 cm(-1) vibronic energy range of the S(1) electronic state, and single vibronic level fluorescence (SVLF) spectra have been acquired by exciting selected levels lying between 750 and 2850 cm(-1) in vibrational energy in the S(1) excited state. Congestion of the dispersed fluorescence in this molecule first appears as the vibrational level energy climbs above 2000 cm(-1). By comparing the SVLF spectra of pDFB-d(4) with those of p-difluorobenzene (pDFB or -h(4)), it is obvious that IVR threshold in -d(4) is localized with a few hundreds cm(-1) lower than that in pDFB. This decrease is entirely due to the increase in vibrational state density due to deuteration.
Laboratory of Physics, Department of Chemistry, University of Bucharest, Blvd. Regina Elisabeta 4-12, Bucharest 1, Romania. marianaduca@yahoo.co.uk
Mariana D
MD
Duca
D001555:Benzene Derivatives / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
D001555:Benzene Derivatives; D005461:Fluorine; D003903:Deuterium