Electron tunneling interfacial

The net interfacial electron flux is the result of many discrete tunneling events between electron levels in phases A and B. Usually, electron tunneling is an elastic process it occurs between an occupied and an empty electron level of the same energy. Hence, the probability of electron tunneling depends on the distribution of the electron levels at both sides of the interface, and on their occupancy. The electronic structure of solids is thus of primary importance for the kinetics of interfacial electron transfer. In analogy, electrochemical electron transfer can be regarded as the result of discrete tunneling events between electron levels in a solid (the elec-... 

Willig and co-workers used near-infrared spectroscopy to measure excited-state interfacial electron transfer rates after pulsed light excitation of cis-Ru(dcb)2(NCS)2-Ti02 in vacuum from 20 to 295 K [208]. They reported that excited-state electron injection occurred in less than 25 fs, prior to the redistribution of the excited-state vibrational energy, and that the classical Gerischer model for electron injection was inappropriate for this process. They concluded that the injection reaction is controlled by the electronic tunneling barrier and by the escape of the initially prepared wave packet describing the hot electron from the reaction distance of the oxidized dye molecule. It appears that some sensitizer decomposition occurred in these studies as the transient spectrum was reported to be similar to that of the thermal oxidation product of m-Ru(dcb)2(NCS)2. 

Electronic Tunneling Factor in Long-Range Interfacial (Bio)electrochemical Electron Transfer... 

All these areas are covered in a broad literature, overviewed, for example in refs. 24 and 25. We do not here address all these elements of molecular charge transfer theory. Instead we discuss the two central factors in the interfacial (bio)electrochemical electron transfer process, first the nuclear reorganization (free) energy and then the electronic tunneling factor. 

The electronic tunneling factor in long-range interfacial (bio)electrochemical electron transfer... 

The vacant interfacial bandgap state formed by hole trapping can be refilled with an electron in two ways by electron donation from a reducing agent in solution, or by capture of an electron from the conduction band. The first process involves iso-energetic electron tunnelling from a suitable non-equilibrium state of the reducing... 

Electrochemical processes at the ITIES involve two basic types of elementary reactions ion transfer and electron tunneling across the liquid liquid boundary. Depending on the properties of the ionic species and the solvents, these two processes can be accompanied by a variety of phenomena such as solvent exchange, interfacial complexation, adsorption, photoexcitation, acid-base dissociation, etc. There are conceptual as well as practical... 

Figure 10.12 A generic energy level diagram of a molecular junction showing the Fermi level of the contacts offset from molecular HOMO and LUMO levels to define interfacial barriers (here, a barrier to hole transport mediated by the HOMO is shown, )). Filled states in the conductors are shaded. A parallel situation can be drawn for electron tunneling (using the LUMO). (Reproduced from Ref. [152].)...

An electronic process, as opposed to an ionic one, has been proposed to explain the photoelectric effect of the chloroplast extract membranes [4, 5, 9,14]. Electron movement across the membrane is explained [9] by dividing the transport process into two parts, electron exchange at the membrane-water interface and electron movement across the bulk membrane. Concepts of electron tunneling used to describe other electrode processes [15, 16] were applied to the interfacial electron transfer process. 

Some care must be exercised when using the reverse saturation current obtained from the semilogarithmic current voltage plot and equation 12 to determine the metal-semiconductor barrier height c()g. Card and Rhoderick have shown that if the interfacial oxide is sufficiently thick so that the electron tunnelling transmission coefficient is no longer unity then the reverse saturation current is reduced to a value equal to the product of the reverse saturation current when no interfacial layer is present and the transmission coefficient of the interfacial oxide> that is... 

Interfacial dipole At a metal-vacuum interface, electron tunnelling into vacuum modifies the electron-electron interactions and weakens the electron-ion interaction ( ee and Eec, respectively, in Equation (1.4.64)). These two processes use up energy when a surface is formed. Lang and Kohn quote the following values 0.43 J/m and 0.5 J/m at a magnesium-vacuum interface, although the latter, calculated in perturbation, is likely to be over-estimated... 

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