Charge light-induced

Interesting results have also been obtained with light-induced oscillations of silicon in contact with ammonium fluoride solutions. The quantum efficiency was found to oscillate complementarity with the PMC signal. The calculated surface recombination rate also oscillated comple-mentarily with the charge transfer rate.27,28 The explanation was a periodically oscillating silicon oxide surface layer. Because of a periodically changing space charge layer, the situation turned out to be nevertheless relatively complicated. 

Clusters Fa tmd Fb can be (photo-)reduced by light-induced charge separation within the RC complex at cryogenic temperatures. Since, under these conditions, only one electron is injected into the Fa/Fb-protein, and since furthermore the EPR spectra of Fa and Fb are significantly different, a straightforward assignment of individual clusters to the cluster-binding motifs in the primary sequence was... 

It is interesting to compare the thermal-treatment effect on the secondary structure of two proteins, namely, bacteriorhodopsin (BR) and photosynthetic reaction centers from Rhodopseudomonas viridis (RC). The investigation was done for three types of samples for each object-solution, LB film, and self-assembled film. Both proteins are membrane ones and are objects of numerous studies, for they play a key role in photosynthesis, providing a light-induced charge transfer through membranes—electrons in the case of RC and protons in the case of BR. 

Photocatalytic oxidation is a novel approach for the selective synthesis of aldehyde and acid from alcohol because the synthesis reaction can take place at mild conditions. These reactions are characterized by the transfer of light-induced charge carriers (i.e., photogenerated electron and hole pairs) to the electron donors and acceptors adsorbed on the semiconductor catalyst surface (1-4). Infrared (IR) spectroscopy is a useful technique for determining the dynamic behavior of adsorbed species and photogenerated electrons (5-7). 

Gerischer, H., and J. Katz (Eds), Light-Induced Charge Separation in Biology and Chemistry, Verlag Chemie, Weinheim, 1979. 

Sineshchekov, O. A. and J. L. Spudich (2004). Light-induced intramolecular charge movements in microbial rhodopsins in intact E. coli cells. Photochem. Photobiol. Sci. 3(6) 548-554. 

Blatter, F. and Frei, H. (1993). Very strong stabilization of alkene-02 charge transfer states in zeolite NaY red-light-induced photooxidation of 2,3-dimethyl-2-butene. J. Am. Chem. Soc. 115, 7501-7502... 

H.Kuhn, Light-Induced Charge Separation in Biology and Chemistry,... 

The desulphurization of disulphides by tervalent phosphorus compounds has been the subject of a review.70 The light-induced desulphurization of benzylic sulphides by phosphites has found further use in the synthesis of cyclophanes which exhibit the formation of intramolecular charge-transfer complexes, e.g. (61) and (62).71... 

Figure 1. Potential energy plot of the reactants (precursor complex) and products (successor complex) as a function of nuclear configuration Eth is the barrier for the thermal electron transfer, Eop is the energy for the light-induced electron transfer, and 2HAB is equal to the splitting at the intersection of the surfaces, where HAB is the electronic coupling matrix element. Note that HAB << Eth in the classical model. The circles indicate the relative nuclear configurations of the two reactants of charges +2 and +5 in the precursor complex, optically excited precursor complex, activated complex, and successor complex.

Raman and IR spectroscopies are complementary to each other because of their different selection rules. Raman scattering occurs when the electric field of light induces a dipole moment by changing the polarizability of the molecules. In Raman spectroscopy the intensity of a band is linearly related to the concentration of the species. IR spectroscopy, on the other hand, requires an intrinsic dipole moment to exist for charge with molecular vibration. The concentration of the absorbing species is proportional to the logarithm of the ratio of the incident and transmitted intensities in the latter technique. 

To account for the periodicity of four in the yield of O2 in a series of flashes (12-13), Kok and coworkers (14) proposed that photosystem II cycles through five states during flash illumination. These intermediate oxidation states are referred to as states (i = 0-4) with the subscript denoting the number of oxidizing equivalents accumulated. The sequential advancement of the S states occurs via the light-induced charge separation in photosystem II. 

Lewis NS (1990) Mechanistic studies of light-induced charge separation at semiconductor/ liquid interfaces. Acc Chem Res 23 176-183... 

Finally, solute radical ions can be generated by light-induced, one-photon or multiphoton ionization of their parent compounds (Chaps. 5 and 16). This approach is particularly useful in the ultrafast studies of short-lived, unstable radical ions that aim to unravel their solvation, recombination, reaction, and vibrational relaxation dynamics of the primary charges (see, e.g., Chap. 10). Whereas the time scale of radiolytic production of secondary ions is always limited by the rate with which the primary species reacts with the dispersed parent molecules, light-induced charge separation can occur in <100 fsec. There are many studies on photoionization of solute molecules in liquid solutions we do not intend to review these works. 

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