Electron tunneling homogeneous

Weinberg WH (1982) Inelastic electron tunneling spectroscopy of supported homogeneous cluster compounds. Vib Spectra Struct 11 1-50... 

In situ STM of metalloproteins with localized low-lying redox levels can be expected to follow ET patterns similar to metalloprotein ET in homogeneous solution and at electrochemical surfaces. The redox level is thus strongly coupled to the protein and solvent environment. A key notion is that the vacant local level (oxidized form) at equilibrium with the environmental nuclear motion is located well above the Fermi levels of both the substrate and tip, whereas, the occupied level (reduced form) at equilibrium is located well below the Fermi levels. Another central notion is that the local redox level at the transition metal centre is still much lower than environmental protein or solvent electronic levels. The redox level therefore constitutes a pronounced indentation in the tunnel barrier. This alone would strongly enhance tunnelling. Configurational fluctuations in the environment can, secondly take the redox level to such low values that temporary physical population occurs. This requires nuclear activation but can still be favourable due to the much shorter electron tunnel distances... 

INELASTIC ELECTRON TUNNELING SPECTROSCOPY OF SUPPORTED HOMOGENEOUS CLUSTER COMPOUNDS, W. Henry Weinberg... 

The photoionization of phenothiazine and its derivatives in SDS micelles, which is not observed in homogeneous solutions and the premicellar region was studied by Gratzel et al. [106-109]. They suppose that the anionic micelles decrease the ionization potential of the phenothiazine derivatives and the photoionization includes an electron tunnelling from the micelle into the solution through the Stem layer. However, there are no direct data for these systems to give a value of the photoionization threshold. A drastic increase of the photoionization quantum yield at the transition to anionic micelles could also be caused by a decrease of the role of the geminate recombination. 

Valette-Hamelin approach,67 and other similar methods 24,63,74,218,225 (2) mass transfer under diffusion control with an assumption of homogeneous current distribution73 226 (3) adsorption of radioactive organic compounds or of H, O, or metal monolayers73,142,227 231 (4) voltammetry232,233 and (5) microscopy [optical, electron, scanning tunneling microscopy (STM), and atomic force microscopy (AFM)]234"236 as well as a number of ex situ methods.237 246... 

An improved and direct correlation between the experimental rate constant and [obtained using Eq. (49)] is observed if v = /zd is used instead of v = 1/Tt, the solvent-dependent tunneling factor is utilized, and only AG (het) of Eq. (8) is used in Eq. (49) (see triangles in Fig. 18). Furthermore, the inverse of the longitudinal solvent relaxation time Xi is not necessarily the relevant one to use as the frequency factor v (see empty circles in Fig. 18). Similar conclusions were reached by Barbara and Jerzeba for the electron transfer reaction in homogeneous solutions. Barbara and Jerzeba measured the electron transfer time... 

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