Optical Reflectivity Measurements on Alloys by Compositional Modulation

A new modulation technique is described which enhances the structure in the spectral reflectivity of metals and alloys. This technique allows the determination of the critical energy for optical interband transitions. The method is applied to various $\alpha$-brass specimens containing between 0.5 and 10 at.% Zn. The threshold energy for interband transitions in these alloys varied between 2.15 and 2.27 eV. The results are compared with those of previous workers obtained by conventional reflectivity measurements.