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 58.63: Poster

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

Characterization of an Effusive High Flux Metal Source and of Pyroelectric Detectors for Nanojoule Adsorption Calorimetry — •Han Zhou, Benedikt Klein, Hans-Jörg Drescher, and J. Michael Gottfried — Fachbereich Chemie, Physikalische Chemie, Philipps-Universität Marburg, 35032 Marburg, Hans-Meerwein-Str.

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 measurement 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 utilizes pyroelectric detectors for the direct measurement of temperature changes in the µK range induced by incremental adsorption. 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 proportional-integral-derivative controlling. Motivated by the general interest in 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 an adsorbate. In addition, the sensitivity of the pyroelectric detectors and its dependence on thermal stress and other factors are systematically studied.