The adsorption of methanol on Ag(111) studied with TDS and XPS

The adsorption of methanol on Ag(111) is studied using thermal desorption spectroscopy (TDS) and X-ray photoelectron spectroscopy (XPS). It is found that methanol adsorbs reversibly. The TDS spectra reveal three different states. These states can be assigned to molecules desorbing from the monolayer, the crystallised multilayers and the two amorphous multilayers which are located between the two other phases. This is the first time that these three states are seen by means of TDS. This multilayer behaviour of methanol most likely also applies to other metals. The sticking coefficient is found to be coverage independent from the submonolayer into the multilayer regime. The desorption energy is found to be 0.41 eV. XPS shows for both the oxygen and carbon a small shift to higher binding energies with increasing exposure.