OPTICAL PROPERTIES OF COBALT

The optical reflectance of Co has been measured in the spectral range 0.05eV≤hν≤11.8eV. The reflectance is low and decreases monotonically in the region hν0.05 eV, indicating that strong absorption has started at photon energies near or below 0.05 eV. The reflectance has small shoulders at about 3.0, 5.0, and 6.0 eV. Optical functions have been deduced from the reflectance data by the Kramers-Kronig analysis. The ωσ curve exhibits a strong structure at hν=6.0 eV, similar to the strong peak at hν=5 eV of ωσ of Ni. The absorption coefficient α of Co also has a prominent peak at hν=6.0 eV and smaller ones at 3.2 and 5.0 eV. These optical data will be used in a separate paper in conjunction with photoemission results to deduce the optical density of states of Co. © 1968 The American Physical Society.