Reutzel Marcel, Lipponer Marcus, Dürr Michael, Höfer Ulrich
Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität , D-35032 Marburg, Germany.
Institut für Angewandte Physik, Justus-Liebig-Universität Giessen , D-35392 Giessen, Germany.
J Phys Chem Lett. 2015 Oct 1;6(19):3971-5. doi: 10.1021/acs.jpclett.5b01510. Epub 2015 Sep 21.
The key parameters of the potential energy curve of organic molecules on semiconductor surfaces, binding energy of the intermediate state and dissociation barrier, were experimentally investigated for the model system of diethyl ether (Et2O) on Si(001). Et2O adsorbs via a datively bonded intermediate from which it converts via ether cleavage into a covalently attached final state. This thermally activated conversion into the final state was followed in real-time by means of optical second-harmonic generation (SHG) at different temperatures and the associated energy barrier ϵa = 0.38 ± 0.05 eV and pre-exponential factor νa = 10(4±1) s(-1) were determined. From molecular beam experiments on the initial sticking probability, the difference between the desorption energy ϵd and ϵa was extracted and thus the binding energy of the intermediate state was determined (0.62 ± 0.08 eV). The results are discussed in terms of general chemical trends as well as with respect to a wider applicability on adsorbate reactions on semiconductor surfaces.
