Infrared Absorptance of Single-Crystal Antimony and Bismuth

Abstract

The absorptance of single-crystal antimony has been measured in the region of 1 to 20 μ at liquid-helium temperatures. There are two independent absorptance maxima depending on crystal orientation and radiation polarization. One maximum is located at 10.6±0.1 μ for the case of the sample binary axis normal to the surface and the radiation electric vector parallel to the bisectrix axis. The other maximum is found at 5.7±0.1 μ for the same crystal orientation, and the electric vector parallel to the trigonal axis. The infrared data are interpreted on the basis of the effective-mass approximation of free carriers. The carrier-independent part of the dielectric constant is found to be ${\epsilon }_0=80\mathrm{}\pm 5$. The infrared data are consistent with a three-band model as proposed by Datars. A very light mass, $m^{*}\approx 0.005m_0$, along the trigonal axis is of particular interest. The bismuth data agree with the previous results of Boyle and Brailsford.