THE INFLUENCE OF CALCULATED PHASE-SHIFTS ON THE PRECISION AND ACCURACY OF ARPEFS-DERIVED STRUCTURAL PARAMETERS

The influence of theoretical atomic scattering phase shifts calculated by different methods in the analysis of angle-resolved photoemission extended fine structure (ARPEFS) data for structural determination of the c(2x2)S/Ni(001) surface was examined, with the goal of assessing b oth the precision and accuracy of derived structural parameters. It wa s found that the values of the S-Ni bond length obtained from the ARPE FS data analysis with different calculated atomic scattering phase shi fts all fall within a total range of 0.02 angstrom (+/- 0.01 angstrom) . This result is also in excellent agreement with the currently accept ed values obtained from low-energy electron diffraction (LEED) and sur face extended X-ray absorption fine structure (SEXAFS), i.e. 2.19-2.20 angstrom. We conclude that this ARPEFS-derived structural parameter i s relatively insensitive to the choice of theoretical atomic scatterin g phase shifts, and is both precise and accurate.