Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)

O 58.62: Poster

Mittwoch, 13. März 2013, 18:15–21:45, Poster B1

Characterization of an Effusive High Flux Metal Source — Han Zhou, Benedikt Klein, Hans-Jörg Drescher, and •J.Michael Gottfried — Philipps-Universität, Marburg

The here presented pulsed molecular / atomic beam source and signal detector are designed for Nanojoule Adsorption Calorimetry (NAC), which is a technique especially suitable for the characterization of non-reversible molecular or atomic adsorption enthalpies on well defined substrates in ultrahigh vacuum. Similar to previous adsorption calorimeters by Černy, King and Campbell, NAC relies on the direct measurement of mircoscopic temperature changes induced by incremental adsorption utilizing pyroelectric detectors. NAC requires long-term stable fluxes at high evaporation rates leading to special requirements on the deposition source, e.g. high volume and constant evaporation temperature established by specially designed evaporator with relatively higher capability of heat generation and proportional-integral-derivative controlling which enables sensitive and non-linear evaporator self-administration. Inspired by the investigations on interfaces between low work-function metals and semi-conducting organic molecules, we here present the characterization of the evaporator regarding the most important parameters as well as the performance of additional pulse-defining devices using Magnesium as adsorbate. In addition the degrading, i.e. the loss of sensitivity, of the pyroelectric detectors due to thermal exposure during bake-outs and the effect of corresponding compensation techniques, i.e. electrical inducement during thermal treatment, were systematically studied.