  We investigate the chemical and structural configuration of acetophenone on
Si(001) using synchrotron radiation core-level spectroscopy techniques and
density functional theory calculations. Samples were prepared by vapour phase
dosing of clean Si(001) surfaces with acetophenone in ultrahigh vacuum. Near
edge X-ray adsorption fine structure spectroscopy and photoelectron
spectroscopy measurements were made at room temperature as a function of
coverage density and post-deposition anneal temperature. We show that the
dominant room temperature adsorption structure lies flat on the substrate,
while moderate thermal annealing induces the breaking of Si-C bonds between the
phenyl ring and the surface resulting in the reorientation of the adsorbate
into an upright configuration.
