Accession Number : ADA262434


Title :   Fast Interfacial Electron Transfer: Evidence for Inverted Region Kinetic Behavior


Descriptive Note : Technical rept.


Corporate Author : NORTHWESTERN UNIV EVANSTON IL DEPT OF CHEMISTRY


Personal Author(s) : Lu, Hong ; Preiskorn, Janice N ; Hupp, Joseph T


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a262434.pdf


Report Date : 19 Feb 1993


Pagination or Media Count : 14


Abstract : Interfacial electron transfer (ET) in a prototypical semiconductor- liquid junction system (aq. Fe(CN)64-/3- with TiO2) can be initiated by directly pumping a molecule to surface charge transfer transition (max = 430nm). The return electron transfer(ET) kinetics, which can be monitored by visible-region transient-absorbance spectroscopy, reveal a well-defined fast component (r = 270ns) and a less well defined slow component (us - ms). Detailed studies in the shorter time regime show that: (1) the interfacial ET rate is independent of laser pump power and, therefore, truly first order, (2) the kinetics are activationless, and (3) the kinetics are inverted, i.e. the ET rate decreases when the free energy driving force is increased by increasing the formal potential of the iron(III)-based electron acceptor. The results are broadly consistent with the predictions of contemporary, multimode quantum rate theories; they are also consistent with the findings of a prior study (by time- dependent scattering) of the Franck-Condon effects accompanying the reaction.


Descriptors :   *QUANTUM THEORY , TRANSIENTS , SCATTERING , PREDICTIONS , SPECTROSCOPY , PHOTOCHEMICAL REACTIONS , LIQUIDS , MOLECULES , ELECTROCHEMISTRY , SEMICONDUCTORS , CHARGE TRANSFER , INVERSION , KINETICS , ELECTRON ACCEPTORS , ELECTRON TRANSFER , TITANIUM DIOXIDE , DECAY , FREE ENERGY , OXIDATION REDUCTION REACTIONS , STATIC ELECTRICITY


Subject Categories : Inorganic Chemistry
      Quantum Theory and Relativity


Distribution Statement : APPROVED FOR PUBLIC RELEASE