The use of the green emission in Er³⁺-doped CaF₂crystals for thermometry application

Abstract

We report here the use of the green upconversion emissions originating from the thermally coupled levels (2)H(11/2) and (4)S(3/2) of the Er(3+) ion in CaF(2):Er (0.01 at.%) for thermometry application in the range 303-423 K. The mechanism responsible for excitation of the green emitting levels is a sequential two-photon absorption process. The fluorescence intensity ratio (FIR) of the green upconversion emissions at wavelengths of about 519 and 551 nm is studied as a function of temperature in the range 303-423 K using a 634 nm tunable dye laser as an excitation source. It is found that the logarithm of the FIR varies linearly with the inverse of temperature. The gap between the two thermally coupled levels (4)S(3/2) and (2)H(11/2) was determined to be about 721 cm(-1). This value is in good agreement with that found by spectroscopic investigations. The calibration curve is established, and the temperature is calculated.

Dual functional NaYF4:Yb3+, Er3+@NaYF4:Yb3+, Nd3+core–shell nanoparticles for cell temperature sensing and imaging

“…An energy gap between the energy levels of 2 H 11/2 and 4 S 3/2 in Er 3+ ions is very narrow, which is separated only by several hundred wave numbers, thus resulting in thermal equilibrium and governed by the Boltzmann factor [24,25]. Therefore, the emission intensities of these bands can be varied with respect to temperature.…”

Temperature measurement based on photoluminescence of Er3+ doped Sr0.3Cd0.7F2 microcrystal coupled to scanning thermal microscopy

“…To ensure that the Boltzmann law can be applied to determine the material temperature, we place this crystal plate in a heater whose temperature is measured by a thermocouple. This heater is equipped with a small aperture through which the laser beam reaches the crystal [11]. The thermal contact is such that the crystal is at the temperature of the heater.…”

Mixing up-conversion excitation behaviors in Er3+/Yb3+-codoped aluminum germanate glasses for visible waveguide devices

“…Up to now, green up-conversion fluorescence produced in rare-earth (RE) ions doped substrates has attracted much attention due to the high color purity in the absence of disturbance from near-infrared (NIR) pump sources. In green up-conversion emitting centers, Er 3+ and Ho 3+ ions act as two outstanding roles, and especially, Er 3+ exhibits more attractive properties owing to the powerful commercial lasers with wavelength ∼980 nm [12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Among the various Er 3+ doped materials, transparent glasses are identified to be more practical substrates for devices due to higher visible light transmittance, which is helpful to reduce transmission loss.…”