Optical property of bovine plasma albumin between 2 and 82 eV.

Abstract

AbstractThe optical constants of bovine plasma albumin in the form of a dry solid film have been determined in the 2–82 eV region of photon energy. The extinction coefficient k was obtained by transmission measurements on thin films on a calcium fluoride substrate and on ultrathin films of polystyrene supported by mesh screen. The refractive index n was determined by a Kramers–Kronig analysis using the measured values of k. The complex dielectric function ε and the energy‐loss function −Im(1/ε) for charged particles were derived from the data of n and k. The result for k exhibit, in addition to the well‐known absorptions at 4.4, 5.5, and 6.4 eV, a small peak at 7.6 eV, a shoulder around 9.7 eV, and a strong peak at 14.0 eV. A prominent peak at 22.7 eV in the energy‐loss function exhibits a large degree of collective nature.