The luminescence spectra of upconversion NaYF4:Yb, Er nanoparticles located under layers of biological tissue of different thickness were experimentally obtained. Luminescence of the particles was excited by laser radiation with a wavelength of 980 nm through a layer of biological tissue. The radiation power was 0.5 W. Luminescence was collected using a collimator with an aperture of 0.15 located at a distance of 20 cm from the sample. The spectra were recorded using a QE 65000 spectrometer (Ocean Optics, US). As the tissue samples, layers of rat skin, muscle and adipose tissue were used. The thicknesses of the samples were varied in the range of 1-2 mm. Distortions of the luminescence spectra resulting from its attenuation in an absorbing-scattering sample are shown. The dependences of distortions on the type and thickness of the sample, as well as on the luminescence wavelength, are obtained. The results obtained are important in determining the temperature of nanoparticles from the luminescence spectra, since the distortions of the spectra lead to an error in determining the temperature.
|