Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 79: Experimental methods
O 79.4: Vortrag
Donnerstag, 29. März 2012, 16:45–17:00, A 060
Time-resolved Nanojoule Adsorption Calorimetry — •Ole Lytken1, Hans-Peter Steinrück1, Hans-Jörg Drescher2, and J. Michael Gottfried2 — 1Universität Erlangen-Nürnberg — 2Universität Marburg
In a typical nanojoule adsorption calorimeter, the average heat of adsorption of a small pulse of molecules is measured as a temperature change in a thin single-crystal sample. The temperature change is often measured using a pyroelectric polymer pressed gently against the backside of the sample. For calibration of the calorimeter, a laser beam with known intensity is used to deposit a known amount of heat in the sample. This calibration works well when the reaction studied is fast. If, however, the initial fast adsorption is followed by a slower secondary reaction, such as a slow desorption, dissociation or segregation into the sample, the shape of the measured signal and the calibration signal start to deviate. Here we will present a method to analyze calorimeter signals which include such slow reactions and extract information, not only of the total amount of heat deposited in a given pulse, but also kinetic information about the slow reaction.