title: Sensitivity of photoelectron diffraction to conformational changes of adsorbed molecules: Tetra-tert-butyl-azobenzene/Au(111).
abstract: Electron diffraction is a standard tool to investigate the atomic structure of surfaces, interfaces, and adsorbate systems. In particular, photoelectron diffraction is a promising candidate for real-time studies of structural dynamics combining the ultimate time resolution of optical pulses and the high scattering cross-sections for electrons. In view of future time-resolved experiments from molecular layers, we studied the sensitivity of photoelectron diffraction to conformational changes of only a small fraction of molecules in a monolayer adsorbed on a metallic substrate. 3,3',5,5'-tetra-tert-butyl-azobenzene served as test case. This molecule can be switched between two isomers,transandcis, by absorption of ultraviolet light. X-ray photoelectron diffraction patterns were recorded from tetra-tert-butyl-azobenzene/Au(111) in thermal equilibrium at room temperature and compared to patterns taken in the photostationary state obtained by exposing the surface to radiation from a high-intensity helium discharge lamp. Difference patterns were simulated by means of multiple-scattering calculations, which allowed us to determine the fraction of molecules that underwent isomerization.
authors.affiliation: Physik-Institut, Universität Zürich , Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Schuler
authors.affiliation: Physik-Institut, Universität Zürich , Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Greif
authors.affiliation: Département de Chimie, Ecole Normale Surpérieure , 24, Rue Lhomond, 75005 Paris, France.
authors.forename: A P
authors.initials: AP
authors.lastname: Seitsonen
authors.forename: G
authors.initials: G
authors.lastname: Mette
authors.affiliation: Physik-Institut, Universität Zürich , Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: L
authors.initials: L
authors.lastname: Castiglioni
authors.affiliation: Physik-Institut, Universität Zürich , Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Osterwalder
authors.affiliation: Physik-Institut, Universität Zürich , Winterthurerstrasse 190, 8057 Zürich, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Hengsberger