Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 43: Adsorption an Oberflächen IV

O 43.5: Vortrag

Freitag, 12. März 2004, 12:15–12:30, H36

A HREELS, TPD and LEED investigation of crotonaldehyde on Pt(111). — •Alexander Krupski, Jan Haubrich, Conrad Becker, and Klaus Wandelt — Institut für Physikalische und Theoretische Chemie, Wegelerstrasse 12, D-53115 Bonn, Germany

TPD studies of crotonaldehyde adsorbed on Pt(111) at 100K were performed for masses between 1 and 100 amu as a function of exposure. Only fragments of the masses 2, 28, 39, 41 and 70 were detected up to 800K. The results show the desorption of molecular crotonaldehyde at 175K (monolayer), 164K (2nd ads. state) and 143K (multilayer). A very weak signal is observed for propylene fragments (39, 41) around 335K. A signal at 28 amu is seen around 395K, saturating already below the monolayer exposure. Two signals are detected for molecular hydrogen desorption around 291K and 425K. The HREEL spectra measured between 100K and 175K show a close relationship to the gasphase data. By contrast, the irreversibly adsorbed species, remainig above 175K, shows besides some shifts sizeable changes in scattering intensities. Vibrations of molecular CO evolve between 300K and 350K in the HREEL spectra, indicating the decarbonylation of the surface species. Above 375K only traces of hydrocarbon species can be observed by HREELS.