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.
Duca
Mariana D
MD
Laboratory of Physics, Department of Chemistry, University of Bucharest, Blvd. Regina Elisabeta 4-12, Bucharest 1, Romania. marianaduca@yahoo.co.uk
D001555:Benzene Derivatives / Q000737:chemistry*; D003903:Deuterium / Q000737:chemistry*; D005461:Fluorine / Q000737:chemistry*; D013050:Spectrometry, Fluorescence
D001555:Benzene Derivatives; D005461:Fluorine; D003903:Deuterium