Fluorescence Characteristics Of Thulium And Neodymium Ions Under Dual-Wavelength Excitation

Under the excitation of near-infrared light,the rare earth up-conversion luminescent material can emit visible light or near-infrared light.Due to rare earth elements have unique advantages in luminescence,rare earth luminescent materials can be widely used in solar cells,energy-saving lighting,military facilities,anti-counterfeiting safety,fluorescent probes,temperature sensing and many other disciplines.Although rare earth luminescent materials have the advantages of integrating with the above disciplines,the luminous advantages have not been fully developed,because under the traditional single excitation of the pump light source,Generally by changing the doping content of rare earth elements,and changing the doping composition of rare earth elements to enhance the luminous intensity and tune the luminous color,so there are still defects such as low luminous intensity,insufficient luminous color,non-dynamically tunable luminous color,and single function,which limit its application in biomedicine or information encryption and other fields.In order to solve the above problems,this article has carried out the following work.（1）Rare earth nanoparticles Tm/Yb:NaYF₄ are excited by dual excitation（980 nm and 800nm）to enhance the up-conversion luminescence intensity of Tm³⁺,and the up-conversion luminescence mechanism of Tm³⁺under dual excitation is analyzed in detail.And the reason for the prolonged fluorescence lifetime.The dual excitation strategy can expand the absorption range of the solar cell,and at the same time can generate stronger visible light,which is beneficial to improve the photoelectric conversion performance of the solar cell.The two blue emission bands of Tm³⁺can not only control the luminous intensity ratio,but also the apparent up-conversion luminous signal can be transmitted through the brightness and color of light,and the hidden signal can be transmitted through the ratio of luminous intensity.Therefore,this dual excitation strategy can become a new type of information encryption technology.（2）The rare earth core-shell structured nanoparticles Tm/Yb:Y₂O₃-Pb S@Si O₂ are excited by dual excitation（980 nm and 800 nm）in order to enrich the luminescence color of rare earth luminescent materials.Tm³⁺is mainly blue luminescence,and its blue-red tuning range is smaller than in the traditional single excitation mode,but under dual excitation,the red luminescence of Tm³⁺increases with the increase of excitation power at 800 nm,mainly because of Pb S The quantum dot absorbs the energy of the 800 nm laser and emits it in the form of heat to realize the blue-red tuning of Tm³⁺.The color tuning of this dual excitation strategy does not need to change the doping concentration and belongs to all-optical adjustment.（3）Using dual excitation（1530 nm and 800 nm）for core-shell structured nanoparticles Nd/Yb:NaYF₄@NaYF₄@Na Pr F₄ to achieve the regional functionalization of rare earth luminescent materials,and for the first time achieving heating function in the Pr³⁺heavily doped nanoparticles.In this paper,it is found that Pr³⁺has an excellent heating effect under the excitation of 1530 nm,and under the excitation of 800 nm,the change in the fluorescence lifetime of Nd³⁺/Yb³⁺can be used to feedback the temperature change in real time.Therefore,nanoparticles heavily doped with Pr³⁺can become a new type of nano heater.