Adsorption of Fe(CO)5 on Si(1 1 1) and adsorbate induced surface reorganisation at low temperatures: a THREELS study

We have studied the adsorption of Fe(CO)5 on the Si(1 1 1)7 × 7 surface at 100 K using high resolution electron energy loss spectroscopy (HREELS), Auger spectroscopy (AES) and low energy electron diffraction (LEED). The data, taken at low temperatures, indicate dissociative adsorption of the Fe(CO)5 molecule resulting in a configuration of a linear FeCO species adsorbed in perpendicular position to the Si(1 1 1) substrate. Exceeding a critical coverage, a spontaneous self-sustained dramatic change of the loss spectra was monitored in real time using time resolved HREELS (TREELS). It is explained by an activated adsorbate induced process changing the electronic and geometric structure of the system, as suggested by off-specular measurements and elastic reflectivity data.