Formation and properties of thin Mo and Mo oxide nanoparticle films

•Mo oxide films of different sized nanoparticles were deposited onto Au/Mica surface.•The chemical composition, electronic and optical properties were studied.•The absorbance window is shifted to smaller wavelengths comparing to bulk. The paper presents a study of thin Mo films, consisted of individual nanoparticles of 3.5–5.5 nm in diameter. Their chemical, electron, and optical properties are studied. It is shown that thin films consisting of individual Mo nanoparticles can be formed from the gas phase by magnetron sputtering. Atmospheric exposure leads to the formation of MoOx oxide shell around the metal nuclei of Mo nanoparticles in the films and changes in its electronic structure. Optical properties of the obtained films consisted of ‘core–shell’ Mo@MoOx nanoparticles are investigated. It is shown that the absorption window falls on the range of 190–300 nm, which can be used in the development of single-photon detectors sensitive to weak ultraviolet signals from long-live states, for example from Th-229 low-lying isomeric state.