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    Applied Surface Analysis Monday Sessions
       Session AS-MoA

Paper AS-MoA2
Optimized Analysis of Spectra: Application of Reciprocal-space Approaches to Broad, Sparse, and/or Multistructured Spectra

Monday, October 29, 2001, 2:20 pm, Room 134

Session: Quantitative Analysis and Data Interpretation II: Electron Spectroscopies
Presenter: D.E. Aspnes, North Carolina State University
Authors: D.E. Aspnes, North Carolina State University
S.D. Yoo, Serome Ventures, Inc., Seoul, Korea
Correspondent: Click to Email
Using a procedure that we recently developed to remove endpoint-discontinuity artifacts in reciprocal-space (R-S) analysis of optical spectra, we solved the optimization problem for determining critical-point (CP) parameters for isolated structures and found that parameters such as CP energies could be obtained for a wide class of direct-space lineshapes even if the lineshapes were not known a priori.@footnote 1@ Here, we extend this work to the analysis of spectra that contain structures that are broad, such as those encountered in photoemission, that are sparse (those that are represented by only a few data points), such as Raman spectra obtained with array detectors, or that contain a multiplicity of CP structures, such as those encountered in optical spectra at higher energies. For the multiple-CP case the advantages of R-S analysis are retained. We obtain a simple expression that describes the effect of overlayers on the CP energies obtained from optical spectra. For sparse spectra and those containing broad structures R-S analysis shows, not surprisingly, that the information content is low and the most efficient approach appears to be to assume a lineshape and perform curvefitting in direct space as is currently done. Extensions of the approach to two or more dimensions, of interest to image processing, are also discussed. @FootnoteText@ @footnote 1@S. D. Yoo and D. E. Aspnes, J. Appl. Phys. (in press).