Dependence of optical temperature sensing and photo-thermal conversion on particle size and excitation wavelength in β-NaYF4:Yb3+, Er3+ nanoparticles

Upconversion luminescence and temperature sensing properties of NaGd(WO4)2:Yb3+/Er3+@SiO2 core–shell nanoparticles

“…This technique is independent on variations of sample concentration and intensity uctuation. 7,8 The energy difference is required to be in the range of 200-2000 cm À1 to enable a Boltzmann distribution for the population ratio of two neighboring excited states. 9 The Yb 3+ and Er 3+ ions are the most popular ion couple to realize UC luminescence.…”

Realization of an Optical Thermometer via Structural Confinement and Energy Transfer

“…Under the conditions of temperature change, various dependency performances of Bi 3+ and Eu 3+ have been obtained. Three modes between 3 P 1 → 1 S 0 and 5 D 0 → 7 F 1 (mode 1), 3 P 1 → 1 S 0 and 5 D 0 → 7 F 2 (mode 2), and 3 P 1 → 1 S 0 and 5 D 0 → 7 F 4 (mode 3) can be employed as sensitive routes for monitoring temperature. The FIR equation (deduced by Struck and Fonger theory) is given as follows: 2 As shown in Figure 10d−f, the S a values become larger in the range of 298−523 K. The data reach maximum values of 0.027 K −1 (mode 1, I 590nm /I 446nm ), 0.067 K −1 (mode 2, I 621nm /I 446nm ), and 0.066 K −1 (mode 3, I 705nm /I 446nm ) at 523 K. The change of S r is interrelated to S a and FIR derived from eq 7, and its maximal values are given as follows: 1.14% K −1 (mode 1, I 590nm /I 446nm ), 1.27% K −1 (mode 2, I 621nm /I 446nm ), and 1.26% K −1 (mode 3, I 705nm /I 446nm ) at 298 K. Compared with the S a /S r of mode 1 and mode 3, the S a and S r obtained by mode 2 are higher.…”

“…Temperature has significant influence on daily life, industrial processes, and scientific research. − Therefore, it is compulsory to measure or detect the temperature quickly and accurately. , Recent studies concerning the fluorescence intensity ratio (FIR) technique have provided a new way for thermal sensing due to its fast responsive rate, superior sensitivity, and simple operation. , Especially, in terms of harsh environments or micro- and high-speed moving objects, FIR fluorescent sensors have significant advantages as compared to conventional contact temperature measurement methods such as noninvasiveness and anti-environment interference. , In general, the FIR temperature measurement is realized by monitoring the relative ratio variation of two distinct emission intensities relative to temperature, which will be effective to circumvent the influence of the emission intensity variation induced by other factors . Most of the FIR fluorescent sensors are based on the temperature-induced inverse electron population at thermally coupled levels (TCLs) from traditional lanthanide elements including Gd 3+ , Ho 3+ , Er 3+ , and Tm 3+ ions. − However, such reported optical thermometers generally have very low signal discriminability.…”

Laser Pyrolysis Synthesis of Upconverting Lanthanide-Doped NaYF4 Nanocrystals for Anticounterfeiting Applications

“…The most common and effective sensitizer is ytterbium­(III), while several different rare-earth ions can be used as upconverters to emit light over different wavelength ranges for specific applications. For example, thulium­(III) with near-infrared (NIR) emission at 800 nm has been used for deep tissue imaging in rodents, based on the relative transparency of tissues at both 980 nm excitation and 800 nm emission wavelengths. , Using erbium­(III) as activator leads to emission at shorter wavelengths near 650 and 550 nm, which are appropriate for display applications and temperature sensing based upon the temperature-dependent ratio of emission at the different wavelengths . Furthermore, co-doping with ytterbium­(III) and holmium­(III) leads to intense upconversion emission at 550 nm, near the peak of human eye sensitivity, making the upconverting nanocrystals (UCNCs) appropriate for the applications that require enhanced visible luminescence intensity like lead detection in water .…”

“…20,21 Using erbium(III) as activator leads to emission at shorter wavelengths near 650 and 550 nm, which are appropriate for display applications and temperature sensing based upon the temperature-dependent ratio of emission at the different wavelengths. 22 Furthermore, co-doping with ytterbium(III) and holmium(III) leads to intense upconversion emission at 550 nm, near the peak of human eye sensitivity, making the upconverting nanocrystals (UCNCs) appropriate for the applications that require enhanced visible luminescence intensity like lead detection in water. 23 In addition, lanthanidedoped nanocrystals upconverting light from NIR to visible wavelength can be used for anticounterfeiting applications, which involve various deposition or printing processes.…”