Femtosecond fluorescence studies of two-dimensional dynamics in photoexcited Michler's ketones

• Published in: Chemical physics letters Vol. 363; no. 1; pp. 189 - 197
• Main Authors: van Veldhoven, E, Zhang, H, Rettig, W, Brown, R.G, Hepworth, J.D, Glasbeek, M
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 02.09.2002; Elsevier Science
• Subjects: Atomic and molecular physics; Exact sciences and technology; Fluorescence and phosphorescence spectra; Fluorescence and phosphorescence; radiationless transitions, quenching (intersystem crossing, internal conversion); Molecular properties and interactions with photons; Physics; Fluorescence spectrum; Temperature dependence; Chemical solution; Stokes shift; Upconversion; Ketones; Experimental study; Luminescence decay; Emission spectra; Benzenic compound; Absorption spectra; Organic compounds; Solvent effects
• ISSN: 0009-2614; 1873-4448
• DOI: 10.1016/S0009-2614(02)01176-4

Femtosecond fluorescence upconversion experiments are reported for two diphenyl ketone dye molecules, the unbridged Michler's ketone [4,4 ′-bis( N,N-dimethylamino)-benzophenone] and its bridged derivative compound 3,6-bis(dimethylamino)-10,10-dimethylanthrone (BMK). For Michler's ketone (MK), in alcoholic solution, anomalously fast dynamic Stokes shifts and fluorescence decay transients are observed. It is discussed that phenyl-group twisting as well as solvation determine the excited-state relaxation dynamics of MK. In the case of BMK, twisting is absent and the excited-state dynamics is determined solely by (fast) initial solvation followed by population decay to the ground state.