R to DF
by Wolfgang Theiss
Juli 2000
M. Theiss - Hard- and Software for Optical Spectroscopy
Dr.-Bernhard-Klein-Str. 110, D-52078 Aachen, Germany
Phone: + 49 241 5661390 Fax: + 49 241 9529100
e-mail: theiss@mtheiss.com
web: www.mtheiss.com
Purpose
R to DF is a program to determine the dielectric function of a material from its halfspace intensity reflectance spectrum. To do this, the unknown phase of the amplitude reflectance coefficient is reconstructed from the intensity spectrum using the Kramers-Kronig relation (KKR) between the known real part and the unknown imaginary part of an analytic complex function. From the complex amplitude reflection coefficient the dielectric function is computed in the final step.
The KKR analysis requires the reflectance spectrum to be known in a wide spectral range which requires an extrapolation of the measured data to zero frequency and to infinity. These extrapolations are done by user-defined spline interpolations or user-defined functions.
The background of this method is discussed shortly at the end of this help.