Optical properties of CdS–PbS films and the possibility of the photoeffect in the mid-infrared range

The possibility of using the plasma resonance in semiconductors to excite exoelectron photoemission in the mid-infrared spectral range without special cooling is discussed. Optical reflection spectra in the mid-infrared range of vacuum-deposited radiation-resistant films of limited CdS–PbS solid solutions containing a minimum associated with the plasma resonance are presented. The plasma resonance of secondary-electron emission is compared with the secondary-ion photoeffect and a conclusion is made concerning the possibility of the influence of the plasma resonance in the mid-infrared range on the escape of electrons from the semiconductor photocathode at room temperature.