Measurement method for energy level radiation-free relaxation coefficients of sensitized ions and activated ions in ytterbium and erbium co-doped sodium yttrium fluoride nanocrystal

Abstract

The invention provides a measurement method for energy level radiation-free relaxation coefficients of sensitized ions and activated ions in an ytterbium and erbium co-doped sodium yttrium fluoride nanocrystal and belongs to the field of fluorescence imaging application of rare-earth doped up-conversion nanocrystals, aiming at solving the problem that the energy level radiation-free relaxation coefficient W of rare-earth ions cannot be measured through an existing method. The measurement method comprises the following steps: firstly, preparing a nanocrystal with a core-shell-shell structure; taking a NaYF4 core as the center, covering the outer side of the center with a NaYF4:Yb<3+>,Er<3+> luminous layer and taking a NaYF4 shielding shell layer as the outermost layer to obtain the nanocrystal with the core-shell-shell structure; measuring a time-resolved spectrum curve of the sensitized ions and the activated ions of the nanocrystal to obtain service life values of the sensitized ionsand the activated ions; obtaining the energy level radiation-free relaxation coefficients of the sensitized ions and the activated ions respectively according to an energy level radiation theoreticaltransition probability A=A0+W. The measurement method provided by the invention gives a relation between the environment and the energy level radiation-free relaxation coefficients and an optimal shielding shell layer thickness is determined, so that the up-conversion luminous efficiency of the rare-earth ions is improved.

Description

technical field [0001] The invention belongs to the application field of fluorescence imaging of rare earth-doped up-conversion nanocrystals, and specifically relates to NaYF 4 :Yb 3+ ,Er 3+ Middle sensitizing ion Yb 3+ and the active ion Er 3+ A method for the measurement of energy-level nonradiative relaxation coefficients. Background technique [0002] Rare earth-doped fluoride nanocrystals have unique properties, such as rich spectra, no autofluorescence, no photobleaching, and no toxicity, etc., which have potential applications in the field of biomedicine, especially bioluminescent imaging. In recent years, rare earth-doped upconversion nanocrystals have attracted much attention, especially NaYF 4 :Yb 3+ ,Er 3+ For nanocrystals, the up-conversion process needs to be excited by 980nm near-infrared light. The biological tissue transmission window is just in this range (800nm-1100nm), and the absorption of 980nm light is very low. The tissue permeability of excitat...

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the current existing (difficult) measurement of the rare earth ion energy level non-radiative relaxation coefficient W is proposed, and the core-shell (NaYF 4 / NaYF 4 :Yb 3+ ,Er 3+ / NaYF 4 ) Special nanostructures to adjust the influence of the external environment on the energy level of rare earth luminescent ions, and measure the transition probability of the energy level under different environmental influences, and then calculate the non-radiative relaxation coefficient W of the energy level

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