ALBERT — All Library Books, journals and Electronic Records Telegrafenberg

1

Digitale Medien

Fluorescence quenching by reversible excimer formation: Kinetic study on the basis of generalized, non-Markovian rate equations (1999)

Naumann, Wolfgang

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 111 (1999), S. 2414-2422

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The kinetics of fluorescence quenching by reversible excimer formation has been studied theoretically on the basis of generalized, non-Markovian rate equations derived from a diffusion-kinetic hierarchy approach in the low-reactant density limit. It is demonstrated that, in contrast to the case of reversible excitation transfer [W. Naumann, J. Chem. Phys. 110, 3926 (1999)], compact rate kernel expressions can be derived not only for contact encounters but also for more realistic, longer-range reactivities. Given as functionals of so-called phenomenological excimer formation and dissociation coefficients, the rate kernel expressions allow a critical assessment of approximations based on time-scale separation arguments. An effective excimer formation coefficient is defined, which leads to simple and physically transparent formulas for the Laplace transforms of the excited monomer and excimer concentrations. The effect of the back reaction on the total fluorescence yield is discussed. The study also includes a critical comparison to analogous results obtained for the case of reversible energy transfer quenching. © 1999 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.479519

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

2

Digitale Medien

Fluorescence quenching by reversible excitation transfer: Application of a hierarchy approach to a pseudo first-order model (1999)

Naumann, Wolfgang

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 110 (1999), S. 3926-3937

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: Fluorescence quenching by reversible excitation transfer is studied for a pseudo first-order model allowing only geminate-type back transfers from the acceptor to the donor. For the theoretical treatment a diffusion-kinetic hierarchy approach is applied derived on the base of reactive many-particle equations. It is demonstrated that the obtained nonlinear system of rate and pair equations is in the low concentration limit kinetically equivalent to a description by generalized rate equations (non-Markovian approach). By introducing an effective forward transfer coefficient, analogous to the definition of phenomenological rate coefficients for other type reversible reactions, compact and physically transparent formulas for the evolution of donor and acceptor concentrations during the quenching process are derived. The fluorescence quenching constant is explicitely given for a contact transfer mechanism. It is shown that for longer range transfers the calculation of the fluorescence constant calculation results in the solution of an integral equation. Some analytically solvable limiting cases are indicated and especially a Förster-type transfer is discussed. © 1999 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.478247

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

3

Digitale Medien

Comparison of the Smoluchowski approach with modern alternative approaches to diffusion-influenced fluorescence quenching: The effect of intense excitation pulses (1997)

Naumann, Wolfgang

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 107 (1997), S. 402-407

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: For low intensity excitation pulses, the fluorescence intensity in the presence of quenchers is obtained, within the framework of the Smoluchowski approach, by convoluting the pulse profile with the survival probability of an excited fluorophore initially surrounded by an equilibrium distribution of quenchers. This conventional approach is generalized to handle excitation pulses of arbitrary intensity. The resulting expression is exact in the limit that the fluorophore is static and the quenchers diffuse independently. Modern alternative approaches to this problem are based either explicitely or implicitely on truncating the reduced many-particle distribution function hierarchy by means of a superposition approximation. For a delta-function excitation pulse all approaches yield the identical result. For arbitrary pulses, the modern approaches predict different, albeit numerically similar, results. This difference, however, does not constitute an improvement over the Smoluchowski approach. Rather, it is a reflexion of an additional approximation that is made in the modern approaches. © 1997 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.474401

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

4

Digitale Medien

Monomer-excimer kinetics in solution. III. Generalized Smoluchowski approach (1995)

Molski, Andrzej ; Naumann, Wolfgang

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 103 (1995), S. 10050-10057

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: A generalized Smoluchowski approach developed in A. Molski, Chem. Phys. 182, 203 (1994) is employed to study reversible excimer formation in solution. For contact excimer formation, relations among the rate coefficients are analyzed for three modes of excitation; initially pulsed, steady-state, and periodic. A new kinetic Laplace transform relation for the frequency domain is demonstrated in the linear harmonic regime. The Laplace transform relations between the time domain and steady states, derived in W. Naumann and A. Molski, J. Chem. Phys. 100, 1511, 1520 (1994) for interaction-free models, are shown to be also valid when the interaction forces are included. © 1995 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.469907

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext

5

Digitale Medien

Molecular and phenomenological rate coefficients of fast reactions in solutions (1995)

Naumann, Wolfgang ; Molski, Andrzej

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 103 (1995), S. 3474-3480

zur Merkliste hinzufügen auf der Merkliste

Details

ISSN: 1089-7690

Quelle: AIP Digital Archive

Thema: Physik , Chemie und Pharmazie

Notizen: The paper is concerned with the problem of formulating chemical rate equations for reversible reactions in solution in terms of concentration-independent, phenomenological rate coefficients. These time-dependent rate coefficients approach, after an initial transient, the rate constants that can be obtained in a relaxation experiment. We start with the coupled evolution equations for the macroscopic concentrations, and for the two-particle distribution functions describing association–dissociation (A+B=C), bimolecular isomerization (A+B=B+C), and double decomposition (A+B=C+D). The effects of interparticle forces and long-ranged reactivity are included. We derive general identities linking the reactants and products radial distribution functions. For association–dissociation this leads to relations among the molecular rate coefficients which are valid for both contact and long ranged reactivities. For the other two reaction types, we were able to derive analogous relations only for contact reactivities. We demonstrate how the phenomenological rate coefficients can be defined via the solutions of the corresponding diffusional boundary-value problems. This approach is quite general, and valid for both contact and long-ranged reactivities and if interaction forces are included. © 1995 American Institute of Physics.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1063/1.470231

Permalink

	Standort	Signatur	Erwartet	Verfügbarkeit

Andere fanden auch interessant ...

Artikel (Nationallizenzen)

Volltext