Accession Number : ADA294316

Title :   Electric Field-Induced Transitions of Amphiphilic Layers on Hg Electrodes.

Descriptive Note : Interim technical rept. no. 3, Jun-Dec 94,

Corporate Author : UTAH UNIV SALT LAKE CITY DEPT OF CHEMISTRY

Personal Author(s) : Gao, Xiaoping ; White, Henry S. ; Chen, Shaowei ; Abruna, Hector D.

PDF Url : ADA294316

Report Date : 31 MAR 1995

Pagination or Media Count : 43

Abstract : There are numerous examples in the literature of amphiphilic molecules which, when adsorbed onto mercury electrodes, undergo electric field-induced transitions between different molecular conformations. In general, very sharp and reversible voltammetric features associated with these transitions are observed when the electrode potential is scanned in the negative direction, typically over the range of -0.30 to - 1.50 V vs SCE, although no redox center is active in these molecular assemblies within this potential range. Using simple electrostatic and thermodynamic arguments, an analytical expression is derived that allows the voltammetric response to be computed in terms of possible molecular conformational changes of the monolayer. The magnitude, shape, and potential of the voltammetric wave are dependent upon molecular parameters (e.g., charge distribution, dimensions and dielectric properties of the amphiphile), surface coverage, and non-electrostatic energy contributions. A peak-shaped voltammetric response is shown to be consistent with the redistribution of charged sites within the amphiphilic layer in response to the surface electric field. Numerical results are in qualitative agreement with voltammetric data for dioleoylphosphatidylcholine (DOPC) adsorbed onto mercury electrodes. jg

Descriptors :   *ELECTRIC FIELDS, *ELECTRODES, *MERCURY, *TRANSITIONS, *PHOSPHOLIPIDS, SCANNING, MEMBRANES(BIOLOGY), BIOLOGY, MOLECULES, ADSORPTION, SITES, NUMERICAL ANALYSIS, ELECTROCHEMISTRY, SURFACES, DIELECTRIC PROPERTIES, ELECTRIC POWER, VOLTAMMETRY, MOLECULAR PROPERTIES, OXIDATION REDUCTION REACTIONS.

Subject Categories : Physical Chemistry
      Biology
      Inorganic Chemistry
      Electricity and Magnetism
      Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE