Raman and Photoluminescence Spectroscopy Detection of NO₂ gas Adsorbed on ZnO Nanowires

NO2 detection via optical techniques is of significant interest for gaining deeper insight into gas sensing mechanisms. ZnO nanowires represent an excellent model system due to their high surface-to-volume ratio and defect-mediated surface reactivity, which enhance sensitivity to adsorbed species. NO2 adsorption induces charge transfer processes that modulate oxygen vacancy-related states, leading to measurable changes in both Raman spectra and photoluminescence emissions. The effect of NO2 adsorptionon the ZnO nanowires surface was investigated by Raman spectroscopy, observing an increase in the LO phonon band around 550 cm-1, and related to the PL contribution.