Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: Poster: New Instruments and Methods

CPP 15.16: Poster

Dienstag, 27. März 2012, 18:15–20:15, Poster A

Generation of excited electron pulses by silicon–silicon oxide–platinum devices — •Michael Scheele and Detlef Diesing — Fakultät für Chemie, Universität Duisburg-Essen, 45117 Essen, Germany

Thin layer systems as the employed silicon–silicon oxide–platinum devices are used in studies of surface chemical reactions. In socalled chemicurrent measurements the tunneling current of the top electrode through the insulating oxide to the back electrode is monitored in the course of exothermic surface reactions. On the other hand one can push electrons of the back electrode to the top electrode by help of a bias voltage U. These electrons may induce surface reactions due to their intrinsic excess energy e· U. This approach has barely been used yet. The pulsed voltage technique allows the injection of e.g. 3·10¹²e⁻ with a pulse voltage of 4 V for a pulse length of 1  ms. In a first experiment the hot electron induced heating of the top electrode (20  nm platinum) is characterized. The top electrode temperature is accessible simultaneously by measuring the resistivity of the top platinum film. One can thus discriminate between heating and excitation induced effects in surface chemical experiments. The possibility to desorb molecules or induce reactions by use of voltage pulses will provide a new kind of electrocatalyst.