SIMULATION OF ERD SPECTRA FOR A SURFACE WITH A PERIODIC ROUGHNESS

For the purpose of identifying hydrogen isotope distribution in a micr oscopically rough surface, the geometrical effect on elastic recoil de tection (ERD) spectra is examined using an optical grating base coated with a thin film of deuterated polyethylene (CD2). It is shown that t he ERD spectra from such surfaces with a periodic roughness agree well with the simulation spectra using the roughness parameters determined by the simultaneous Rutherford backscattering spectroscopy (RBS) quan tification of the roughness, the ''Pb coating-RBS method''. The micros copic structure of the sample surface is reflected well in the spectra l shape. This means that the true distribution of the hydrogen isotope s in a sample could be determined by correcting the ERD spectra for th e roughness. Potential applicability of the present method, Pb coating of the sample followed by simultaneous RBS-ERD analysis, to correctio n of ERD spectra for the surface roughness is thus demonstrated. (C) 1 998 Elsevier Science B.V.