Adsorbate induced surface resistivity from IR-transmission spectroscopy: oxygen on FerMgO 001/

In situ IR-transmission spectroscopy from 1300 cmy1 to 5900 cmy1 was performed on flat iron ultrathin films on MgO 001.in UHV before and after exposure to oxygen. Spectra of pure Fe films show an absorption that is strongly determined by film–surface scattering of charge carriers. The adsorbate induced IR-optical surface resistivity is observed by a significant broadband increase of transmission. Applying a proper description of the frequency dependent electron scattering rate of iron and including Persson’s surface resistivity model we succeed in explaining this broadband spectral change. We calculate an electron–adsorbate scattering rate, which leads to reasonable values for the dc conductivity of the investigated ultrathin films and for the electron-hole lifetime of adsorbate motion. q1999 Elsevier Science B.V. All rights reserved.