  We present experimental results and theoretical simulations of the adsorption
behavior of the metal-organic precursor Co2(CO)8 on SiO2 surfaces after
application of two different pre-treatment steps, namely by air plasma cleaning
or a focused electron beam pre-irradiation. We observe a spontaneous
dissociation of the precursor molecules as well as auto-deposition of cobalt on
the pre-treated SiO2 surfaces. We also find that the differences in metal
content and relative stability of these deposits depend on the pre-treatment
conditions of the substrate. Transport measurements of these deposits are also
presented. We are led to assume that the degree of passivation of the SiO2
surface by hydroxyl groups is an important controlling factor in the
dissociation process. Our calculations of various slab settings using
dispersion corrected density functional theory support this assumption. We
observe physisorption of the precursor molecule on a fully hydroxylated SiO2
surface (untreated surface) and chemisorption on a partially hydroxylated SiO2
surface (pre-treated surface) with a spontaneous dissociation of the precursor
molecule. In view of these calculations, we discuss the origin of this
dissociation and the subsequent autocatalysis.
