Photoluminescence (PL) of TiO2:Sm3+ thin films was studied at RT. The films were prepared by the sol-gel spin-coating
technique or by atomic layer deposition (ALD) followed by ion implantation. The PL was excited with a Nd:YAG pulse
laser emitting at 355 nm. The spectrum of PL consists of intense Sm3+-specific emission lines with a well-pronounced
fine structure. The influence of different gaseous environments (air, oxygen, nitrogen) or vacuum on the Sm3+ emission
was investigated. In the case of a permanent irradiation of sol-gel films in an oxygen-containing environment, the PL
intensity increased. The increase was significantly large but slow. The subsequent evacuation of the measurement
chamber led to a rapid decrease of the emission below the detection limit. When the oxygen-containing gas was without
any intermediate evacuation replaced by nitrogen, the PL intensity descended to an almost vacuum level. The subsequent
exposure to oxygen led to a rather fast emission recovery. The ALD-prepared films exhibited a similar but markedly
slower response. The fast response observed was attributed to the adsorption of oxygen on the surface, and the slower
one, to the diffusion of oxygen vacancies taking place under the irradiation in the bulk.
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