Geminate dynamics

Papanikolas J M, Gord J R, Levinger N E, Ray D, Versa V and Lineberger W C 1991 Photodissociation and geminate recombination dynamics of t in mass-seiected, (Cfjj j ciuster ions J. Phys. Chem. 90 8028-40... 

Batista V S and Coker D F 1996 Nonadiabatic molecular dynamics simulation of photodissociation and geminate recombination of liquid xenon J. Chem. Phys. 105 4033-54... 

Experiments on 1 -CO using benzene in place of CTAB were also done to examine the effects solvent and environment on the photodissociation. None were found. The photointermediates arrived at the same time, had the same peak wavelengths, extinction coefficients and band shape. In so far as the dynamics observed in these experiments are independent of CO pressure and since there is no detectable geminate CO recombination, it is reasonable to expect effects on the photodissociation due to solvation to be minimal as diffusion has not yet occurred on the time scale studied. 

Muller JG, Lupton JM, Feldmann J, Lemmer U, Scharber MC, Sariciftci NS, Brabec CJ, Scherf U (2005) Ultrafast dynamics of charge carrier photogeneration and geminate recombination in conjugated polymer fullerene solar cells. Phys Rev B 72 195208... 

The lowest energy conformations of dihydro-1,4-thiazine 56 (Figure 5) were calculated by computer using a molecular dynamics simulation and the information was used to calculate the geminal coupling constants <1995JFA2195>. 

Hagen, S. J., Hofrichter, W. A., and Eaton, W. A. 1996. Geminate rebinding and conformational dynamics of myoglobin embedded in a glass at room temperature. J. Phys. Chem. 100 12008-21. 

Therefore, we have developed a pump/pump-probe experiment to obtain more informations on the structures of these geminate ion pairs. It allows the investigation of the excited states dynamics of the transient species at different time delays after photo-triggering the charge transfer, by monitoring the ground state recovery (GSR) of those transient species (Fig. lb). In the present study, we have used perylene (Pe) as fluorescer (electron donor) and either trans-l,2-dicyanoethylene (DCE) or 1,4-dicyanobenzene (DCB) as quencher (electron acceptor) in acetonitrile (ACN). 

When using DCE as quencher (Fig.3a), the second deactivation channel remains open until Ati=l ns. The small free ion yield for this system indicates that charge recombination is much more efficient and therefore much more rapid than charge separation. Furthermore, we know from time resolved fluorescence decay measurements that electron transfer quenching is still not finished at At =lns. Consequently the absorbance should be dominated by fresh geminate ion pairs, over the whole timescale investigated. Thus, the GSR dynamics of Pe + in presence of DCE should be independent of Ati, which is confirmed by our experimental observations. 

Coherent dissociation Geminate recombination Dephasing Proton transfer Electron transfer Vibrational relaxation 8arrierless reactions Bimolecular reactions Ionic reactions Solvation dynamics Friction dynamics Polarization (kerr)... 

The rate of another dynamic process, a conformational ring inversion, depends in particular on the nature of the substituent R at the a-carbon. The geminal exo and endo methylene hydrogens are interchanged by opening of the bridging bond and planarization... 

Excited states (vertical) Solvent effects ESR Solid state dynamics Infinite systems Geminal functional theory... 

Figure 3.21. The same as in Figure 3.20(b) but in a wider dynamic region and for ka — kb — 5ko- The solid line represents the IET, which accounts for the initial geminate and subsequent bimolecular process. The quasiexponential asymptote of the latter (thin straight line) is approached from above. The dashed line is the same kinetics but obtained from the phenomenological YLS theory, which also approaches the bimolecular asymptote (thin line), but from below. (From Ref. 45.)...

The group of Ogenko11 states that geminal silanols do not exist and that the shift in the infrared 3745 cm 1 vibration and the occurrence of the -92 ppm 29Si-NMR peak can be explained by changes in the coordination of the surface Si atoms and electronical interactions between silanols. Smirnov12 on the other hand used the theory of molecular dynamics to prove that the 3745 cm 1 band is a superposition of 2 species. 

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