OPTICAL PROPERTIES OF VACUUM-EVAPORATED SELENIUM AND TELLURIUM

The optical properties of evaporated films of Se and Te at room temperature have been determined in the energy range from 5-25 eV. In addition the real part of the refractive index has been determined for Te up to 38 eV. The films used were of high quality, prepared and measured in vacuum (<2×10 -5 Torr), and reflectances were significantly higher than reported in previous literature. The optical properties of Se and Te are similar; both show structure in the imaginary part εZ of the dielectric constant ε between 7 and 9 eV identified with interband transitions. The calculated energy-loss function - Im(ε+1)-1 shows a maximum at 14.5 eV in Se and at 11.3 eV in Te. The calculated energy-loss function - Im(ε) -1 shows peaks at 5.25 and between 18.5 and 19.0 eV for Se and at 5.6 and 17.2 eV for Te. These optical data agree with published characteristic electron-energy-loss measurements and allow identification of the modes of energy loss involved. © 1968 The American Institute of Physics.