FePc/Au(111) and H 2 O/FePc/Au(111) XPS and XAS Study Cristina Isvoranu Lund University, Dep. of Synchrotron Radiation Research Berlin, October 1 st 2007

Summary - FePc monolayers on Au(111) (XPS, XAS study) - Interaction of water with FePc monolayers on Au(111)

The molecular structure of FePc

XPS principle hνhν Core level Unoccupied valence Occupied Valence EVEV hν=E b +E K +Φ

FePc monolayers - Characteristic XPS peaks

Core level Unoccupied valence Occupied Valence HOMO-2 HOMO HOMO-1 LUMO LUMO+2 LUMO+1 hνhν What happens? Result XAS (NEXAFS) Principle: -maps the unnocupied states - by variation of the photon energy the absorption into the different unoccupied levels is probed

XAS – Proof of Molecular Orientation Dipole selection rule Δl = ±1 must befulfilled. For excitations from the 1s orbital,only states that have a component with p-character at the excitation site are mapped. The scalar product of E (electrical field of the light) and p (linear momentum operator) gives rise to an angular dependence of the cross section that can be used to determine the molecular geometry. E vector Max. cross section Min. cross section

Molecular orientation of FePc Monolayers on Au(111) π*π* σ*σ* Molecular plane parallel to surface NE - E vector normal to the surface hνhν E NI - E vector parallel to the surface E hνhν

Interaction of water with FePc Monolayers on Au(111) Monolayer FePc/H2O/Au(111) Multilayer FePc/Au(111) Monolayer FePc/Au(111) Annealing Dose water Different amounts of water Temperature influence Monolayer FePc/H2O/Au(111)

Water dosing on FePc monolayers on Au(111)

Water desorption

XAS measurements on water/FePc/Au(111) System

Future plans - continue experiments on H 2 O/FePc/Au(111) (XPS and STM) - try H 2 O/FePc/HOPG - finalisation of some XPS, XAS, RPES measurements on FePc/HOPG - interaction of H 2 Pc monolayers with water

Thank You!