Licentiate thesis: Kinetics of C2H2 cyclization to C6H6 at Cu(110) studied by Sum-Frequency Generation
by
Yuliya Nestsiarenka(Stockholm University, Department of Physics)
→
Europe/Stockholm
FB55
FB55
Description
In the present thesis I present build-up of a SFG experiment for vibrational spectroscopy studies of different adsorbate systems as well as reaction kinetics and dynamics. The setup is applied to trimerization of C2H2 at the catalyst Cu(110) where the reaction kinetics is resolved. Four resonant peaks were indentified in the SFG spectrum which was recorded as a function of temperature. At low temperature we observed two peaks which can be explained by previous results as vibration of symmetrically adsorbed molecules. With increasing temperature molecules start to move and form islands, and we observed shift of peaks and appearance of a third peak corresponding to asymmetrically absorbed species. Around 300 K we obtain a maximum of a fourth resonance from the intermediate in the trimerization reaction. Activation barriers for reaction steps are calculated using a kinetic model: 84±6 kJ/mol for the first step reaction (formation of C4H4) and for the second step (creation of C6H6) activation energy less by 5±1 kJ/mol.