The optical constants for the metal listed have been measured by a number of investigators, and there is a large scatter in the reported values for any one metal. Instrumental sources beyond the investigator’s control, e.g. second order radiation or scattered light from the monochromator, are responsible for some of the scatter. Other contributing factors arise from errors in quantities measured and from genuine differences in the samples caused by the methods of preparation.Dr. David W. Lynch and Dr. William R. Hunter in11.
CHOOSING REFLECTIVE INDICES