External Electric Field Effects

One of the most important experimental methods of studying the electron-ion recombination processes in irradiated systems are measurements of the external electric field effect on the radiation-induced conductivity. The applied electric field is expected to increase the escape probability of geminate ion pairs and, thus, enhance the number of free ions in the system, which will result in an enhanced conductivity. 

Calculations of the external electric field effect on the escape probability in multipair clusters [18] have shown that significant deviations from the results of the single-pair theory are expected at high electric fields. At low fields, the escape probability is a linear... 

Computer simulation has also been used to calculate the external electric field effect on the geminate recombination in high-mobility systems [22]. For the mean free time x exceeding -0.05, the field dependence of the escape probability was found to significantly deviate from that obtained from the diffusion theory. Furthermore, the slope-to-intercept ratio of the field dependence of the escape probability was found to decrease with increasing x. Unlike in the diffusion-controlled geminate recombination, this ratio is no longer independent of the initial electron-ion separation [cf. Eq. (24)]. 

T. Ito, 1. Yamazaki, N. Ohta, External Electric Field Effect on Interlayer Vectorial Electron Transfer from Photoexcited Oxacarbocyanine to Viologen in Langmuir-Blodgett Films , Chem. Phys. Lett., 277, 125 (1997)... 

The curves in Fig. 1 demonstrate the decrease of PL intensity (quenching) and the red shift of PL maximum with the voltage increased. At the values of electrical field strength E up to 10 V/cm the PL of nanorods is quenched more than PL of QDs. However, the wavelength shift of PL maximum with applied electric field for nanorods increases very weak. Evidently, due to the elongated shape of nanorods, the external electric field effect may differ for S- and P-polarized PL. This property is important for application of this material in optoelectronic nanodevices. To understand reasons of the electric field effect difference between QDs and nanorods, the mechanism of nanorods PL quenching has to be studied. The quantum-confined Stark effect is probably not the single factor in force. 

External Electric Field Effect on Fluorescence of BCECF... 

Ohta, N., Koizumi, M., Umeuchi, S., Nishimura, Y. and Yamazaki, I. (1996) External electric field effects on fluorescence in an electron donor and acceptor system ethylcarbazole and dimethyl terephfhalate in PMMA polymer films./. Phys. Chem., 100, 16466—16471. 

Nakabayashi, T., Wu, B., Morikawa, T., Iimori, T., Rubin, M.B., Speiser, S. and Ohta, N. (2006) External electric field effects on absorption and fluorescence of anfhracene-(CH2)n-naphthalene bichromophoric molecules doped in a polymer film. /. Photochem. Pholobiol. A, 178, 236-241. 

De Grooth BG and van Gorkom HJ (1981) External electric field effects on prompt and delayed fluorescence in chloroplasts, Biochim. Biophys. Acta 635, 445-456. 

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