Abstract

Many pellets were prepared seperately from Dixon KS-2, HPN-2, 200-10, and Asbury Micro 260 graphite powders which were compressed between polished stainless steel rams at a pressure of 0.67 GPa for 30 min. The most specular reflective pellet surface thus formed from each of the four powders was then selected for further investigation. The mass/unit volume of the pellets was in the 2.02 ± 0.06-g/cm³ range compared with 2.23 g/cm³ for crystalline graphite. Near-normal incidence reflectance spectra R(v) of the four pellets were obtained throughout the 180-50,000-cm^-1 wave-number region. Kramers-Kronig methods applied to R(v) provided complex refractive indices N(v)= n(v)+ ik(v) and dielectric functions ϵ(v) = ϵ₁(v) + iϵ₂(v). The E_1u in-plane and A_2u out-of-plane infrared active vibrational modes showed maxima in the k(v) spectra at 1584 and 864 cm^-1, respectively. These modes were also quite evident in the first derivative of the reflectance spectra. Spectral values of R(v), N(v), and ϵ(v) are presented in graphical form. Differences and similarities to spectra for crystalline graphite are also presented.

© 1985 Optical Society of America