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  • 1990-1994  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 1042-1057 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The dynamical behavior of intramolecular electronic excitation transfer in 9,9'-bifluorene and 2,2'-binaphthyl has been investigated in various solvents using a heterodyned and background-subtracted femtosecond polarization technique. It has been found that the excitation transfer between fluorenyl moieties occurs on a time scale of around 300 fs in hexane, but evidently slows down to around 970 fs in CCl4, and there appears little observable variation in transfer dynamics when the solvent is changed through the hexane–decane–hexadecane series. It has also been found that excitation transfer between naphthyl moieties in CCl4 undergoes damped oscillations which have an apparent period of 1.2±0.1 ps and a damping time constant of 180±20 fs. While there is no clear sign of any oscillation in hexane, the transfer dynamics decays only slightly faster. All the phenomena observed can be neatly categorized, within the simple phenomenological Bloch theory, as either over- or underdamped motion relevant to the ratio of the exciton splitting to the pure dephasing rate. However, it is the thorough analysis of all the secular elements of the Redfield relaxation matrix that pinpoints the role of correlated fluctuations in the excitation transfer, and provides a quantitative relation of the pure dephasing between the excited local states to that between the excited and ground states. The equivalency of the pure dephasing rate between the two local states to the population transfer rate between the two delocalized states also prompts us to propose that a local libration of solvent CCl4 could play a key role in underdamping the excitation transfer coherence.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 98 (1993), S. 9222-9222 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 94 (1994), S. 353-358 
    ISSN: 1434-6036
    Keywords: 64.60.My ; 64.60.Qb ; 51.10+y
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract A nonequilibrium statistical mechanical theory for particle coarsening processes is presented. In this theory, the rate of change of a given particle is determined by both a deterministic and a fluctuation terms, and the particle size distribution (PSD) satisfies Fokker-Planck-type equation. We use a time scaling technique and find the PSD scaled by average particle size as well as the power laws of time dependence of some quantities. The asymptotic scaled PSD is independent of initial condition but does depend on the equilibrium volume fraction. We show that the average radius grows att 1/3 and the density of particles decays ast −1.
    Type of Medium: Electronic Resource
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