Effect of atmosphere on recovery of diffuse reflection spectra of ZnO powder modified with nanoparticles upon irradiation in vacuum

Abstract The changes of diffuse reflection spectra (ρλ) in the range 0.2–2.2 μm and the integral absorption coefficient of solar radiation (as) of ZnO powder modified with SiO2 nanoparticles were studied. These changes were recorded in vacuum at the site of irradiation of the samples (in situ) after irradiation (30 keV electrons, 5 keV protons, and solar spectrum quanta (SSQ)), as well as upon exposure the samples to the atmosphere. It was found that for all types of irradiation, a significant recovery of the ρλ spectra in the near-IR region in the atmosphere is recorded. The recovery is 1.5 times for the samples irradiated with electrons and solar spectrum quanta, and 1.1 times for the sample irradiated with protons. In the visible region, absorption is due to the intrinsic point defects of ZnO, the reflection coefficient is not only not restored in the atmosphere, but it even decreases (1–3%). Mechanism of formation of photo- and radiation defects under these types and parameters of irradiation is explained; the processes of restoration of the ρλ spectra of the modified ZnO powder are considered.