Soft X-Ray appearance potential spectroscopy of C,N and O adsorbed on Cr,Mo and W

The 1s level soft x-ray appearance potential spectra of C, N and O chemisorbed on polycrystalline Cr, Mo and W surfaces have been observed. The adsorbate ls spectra show the following characteristic features in the chemisorption regime: (i) Cr: one single peak; (ii) Mo and W: a doublet structure. We tentatively assume that the doublet structure is due to a splitting in the antibonding levels of the surface complex. Oxidation of Mo and W at high temperature causes changes in the metal $\text{(Mo 2p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{W 3d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)}$ and in the oxygen 1s spectra as compared with the spectra obtained after room temperature adsorption of oxygen.