Analysis of diffuse reflection and absorption spectra of ZnO in the near-IR region

It is established that the absorption of ZnO in the near-IR region of the spectrum is determined by free electrons and chemisorbed gases. The free-electron absorption spectrum is approximated by a power function with an exponent which varies within the range 2-3, depending on the defectiveness of the specimen. Chemisorbed gases yield absorption bands at 1.37; 1.18; 1.08-1.03; 0.95-0.93; 0.85; 0.75-0.73; and 0.65-0.63 eV. The bands at 1.18 and 0.85 eV are due to chemisorbed oxygen in the states O- and O2-, while the other bands can be attributed mainly to atomic hydrogen and OH-groups