Optical constants and spectral specular reflectivity of highly oriented pyrolytic graphite (HOPG). Revision 1.

摘要

Measurements of the specular reflectivity and the optical constants of highly ordered pyrolytic graphite (HOPG) have been made using two independent optical systems. The first measures reflectance (at 1.06 (mu)m and 293 K) by comparing the intensity of a laser beam before and after reflecting off the sample. The second determines the complex index of raft-action (from 0.55 to 8.45 (mu)m, with sample temperatures of 293, 480, 900 and 1300 K) by ellipsometry. Agreement between the two methods is good. Moderate reflectivities are observed over the full spectral range of measurement: the spectral directional-hemispherical reflectivity at normal incidence varies from 0.41 at 0.55 (mu)m to 0.74 at 8.45 (mu)m. The components of the complex index of refraction increase smoothly with wavelength. The index of refraction increases from 3.10 at 0.55 (mu)m to 7.84 at 8.45 (mu)m. The extinction coefficient varies from 2.01 to 6.66 over the same range.