Far-infrared measurements on oriented bismuth deposits have yielded the indexes of absorption and refraction together with the electrical conductivities and dielectric constants, as well as the relaxation times of the holes and electrons in the deposits. The dielectric constants for these deposits have been found to approach the value zero near the wavelength of the reflection minimum. The reduced masses for the electrical carriers derived from the measurements here are found to be in fair agreement with values determined by other methods.
LOUIS HARRIS and JOHN PIPER, "Optical and Electrical Properties of Bismuth Deposits," J. Opt. Soc. Am. 53, 1271-1275 (1963)