Optical Modulation Spectra of Selenium and Their Dependence on the Uniaxial Stress

Wavelength‐ and stress‐modulated reflectance and transmission spectra of selenium are measured at 77 °K in the photon energy range from 1.7 to 3.7 eV. New structure is discovered, e.g. a peak at 2.0 eV in the wavelength‐modulated reflectance spectrum with light polarized parallel to the [0001] direction. Unusually large linear stress coefficients of the peaks are found. The stress coefficient of the sharp exciton peak at 1.97 eV in the wavelength‐modulated reflectance spectrum with light polarized perpendicular to [0001] is +(2.5 ± 0.4) × 10−11 eV cm2 dyn−1 for the uniaxial compression along the [0001] direction, and −(6.7 ± 0.5) × 10−11 eV cm2 dyn−1 for the compression along [1000].