Adsorption of CO on W(001) by high resolution electron spectroscopy

The vibrational modes induced by CO in W(001) at temperatures <= 350 K are detected by means of electron energy loss spectroscopy with resolution in the 6-7 meV range. Two β adsorption regimes are identified depending on coverage. Heating at various increasing temperatures reveals coverage dependant irreversible surface structure modifications. The β spectra after adsorption or desorption are discussed in terms of the usual questions of multiple β states, dissociation, and reconstruction. The α1 and α2 states are detected both by their W-C and C(triple bond)O frequencies. A small signal is assigned to a new α-state, named α3, which may explain some thermal desorption results. (Auth.)