title: The influence of the Tbeta level upon fluorescence and laser properties of aromatic compounds.
abstract: The fluorescence and laser properties of seven specially chosen aromatic compounds are studied at 293 degrees C. The quantum yield of fluorescence, gamma, decay times, tauf, of the deaerated and non-deaerated solutions are measured. The oscillator strength, fe, fluorescence rate constants, kf, natural lifetimes, tauT0, and intersystem crossing rate constants, kST, are calculated. Some laser parameters are calculated or measured experimentally. It is found that the position of the Tbeta level plays an important role in the fluorescence and laser properties of aromatic compounds. If the Tbeta level is situated below the Sp level, it decreases the quantum yield of fluorescence and the decay time and increases the threshold of laser action. If, due to some structural changes of a molecule, the Tbeta level is situated higher than the Sp level, then the quantum yield of fluorescence and the decay times are increasing and the threshold of laser action is decreasing. Such influence of the position of the Tbeta level upon fluorescence and laser properties of aromatic compound is explained by the fact that the Sp level mixes with the Tbeta level more readily than with other taupipi* levels.
authors.affiliation: Physics Department, University of Botswana, Private Bag UB 00704, Gaborone, Botswana.
authors.forename: N
authors.initials: N
authors.lastname: Nijegorodov
authors.forename: D P
authors.initials: DP
authors.lastname: Winkoun
authors.forename: J S
authors.initials: JS
authors.lastname: Nkoma
mesh_terms: D000873:Anthracenes / Q000737:chemistry; D005453:Fluorescence; D007834:Lasers; D015394:Molecular Structure; D009279:Naphthacenes / Q000737:chemistry; D009281:Naphthalenes / Q000737:chemistry; D011084:Polycyclic Aromatic Hydrocarbons / Q000737:chemistry*; D011789:Quantum Theory; D013050:Spectrometry, Fluorescence; D013730:Terphenyl Compounds / Q000737:chemistry
chemical_list: D000873:Anthracenes; D009279:Naphthacenes; D009281:Naphthalenes; D011084:Polycyclic Aromatic Hydrocarbons; D013730:Terphenyl Compounds; C031721:naphthalene; C034020:anthracene; C487736:naphthacene