title: Electron beam induced surface activation of ultrathin porphyrin layers on Ag(111).
abstract: We demonstrate how a focused electron beam can be used to chemically activate porphyrin layers on Ag(111) such that they become locally reactive toward the decomposition of iron pentacarbonyl, Fe(CO)5. This finding considerably expands the scope of electron beam induced surface activation (EBISA) and also has implications for electron beam induced deposition (EBID). The influence of the porphyrin layer thickness on both processes is studied in detail using scanning tunneling microscopy (STM) and scanning electron microscopy (SEM) as well as Auger electron spectroscopy (AES) and scanning Auger microscopy (SAM). While a closed monolayer of porphyrin molecules does exhibit some activity toward Fe(CO)5 decomposition after electron irradiation, a growth enhancement is found for bi- and multilayer films. This is attributed to a partial quenching of activated centers in the first layer due to the close proximity of the silver substrate. In addition, we demonstrate that the catalytic decomposition of gaseous Fe(CO)5 on Ag(111) can be effectively inhibited by introducing a densely packed monolayer of 2H-tetraphenylporphyrin (2HTPP) molecules.
authors.affiliation: Lehrstuhl für Physikalische Chemie II and Interdisciplinary Center for Molecular Materials (ICMM), Friedrich-Alexander-Universität Erlangen-Nürnberg , Egerlandstr. 3, 91058 Erlangen, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Vollnhals
authors.forename: Patrick
authors.initials: P
authors.lastname: Wintrich
authors.forename: Marie-Madeleine
authors.initials: MM
authors.lastname: Walz
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Steinrück
authors.forename: Hubertus
authors.initials: H
authors.lastname: Marbach