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Temperature sensitive properties of Eu2+/Eu3+ dual-emitting LaAlO3 phosphors
摘要： In this study, Eu2+/Eu3+ coexisting perovskite LaAlO3 phosphors were synthesized by a traditional high-temperature solid-phase reaction method and investigated via X-ray diffraction data, X-ray photoelectron spectroscopy and temperature-dependent photoluminescence spectra. The Eu2+/Eu3+ coexisting LaAlO3 phosphors exhibit excellent optical temperature sensing characteristics and are potential inorganic materials for temperature detection. The measured maximal absolute temperature sensitivity reaches 0.014 K-1, and the corresponding largest relative temperature sensitivity is 1.193% K-1, which are superior to most of previous reports of that. Meanwhile, the monitored signal peaks are well separated, providing a good signal discriminability. The energy level crossover relaxation of Eu2+ and Struck-Fonger crossover process involving O2–-Eu3+ charge transfer band were used to explain the different temperature-dependent responses of Eu2+ and Eu3+. This work may give new ideas for the future research of optical thermometric materials with high sensitivity and high discriminability.
关键词： Fluorescence intensity ratio,Charge transfer band,Thermometry phosphor,LaAlO3
更新于2025-11-14 15:13:28
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[IEEE 2018 IEEE 3rd Advanced Information Technology, Electronic and Automation Control Conference (IAEAC) - Chongqing, China (2018.10.12-2018.10.14)] 2018 IEEE 3rd Advanced Information Technology, Electronic and Automation Control Conference (IAEAC) - Dissolved Oxygen Detection Based on Light-to-Frequency Conversion
摘要： In the detection of dissolved oxygen(DO) concentration based on the principle of fluorescence quenching, fluorescence intensity detection generally relies on high-precision instruments, extra amplifier circuits and filter circuits at present, which make the detection cost high and the structure complex. In order to reduce the detection cost, simplify the structure of the detection system and improve the stability of the detection, a method of directly detecting the fluorescence intensity using the light-to-frequency proportional conversion characteristics of TCS3200 sensor was proposed and a DO concentration detection system was designed subsequently. The linear relationship between the output frequency of the sensor and the DO concentration was studied and established, based on which the sample DO concentration can be calculated by using the frequency value collected in the detection system accordingly. The experimental results show that the relative error (RE) between the measured DO concentration and the standard value of the sample is less than 5%, and the relative standard deviation (RSD) of the sample data is less than 2%, both of which meet the requirements of accuracy and precision respectively. At the same time, the detection system avoids complicated circuits and its structure is simple, and has the merit of strong anti-interference ability, low cost and high precision.
关键词： TCS3200 sensor,fluorescence intensity,DO,frequency
更新于2025-09-23 15:23:52
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Assessment of tooth wear based on autofluorescence properties measured using the QLF technology in vitro
摘要： Background: The difference in autofluorescence between enamel and dentine layer has prompted recommendations to use the quantitative light-induced fluorescence (QLF) method for quantifying tooth wear (TW). This study investigated the potential of QLF for distinguishing the severity of occlusal TW based on differences in the autofluorescence intensity. Methods: In total, 106 extracted permanent molars and premolars having suspected wear without pulp exposure were used. The severity of wear was determined by visually examining all teeth using the tooth wear index (TWI) of Smith and Knight. QLF images were captured and converted into 8-bit grayscale images. The difference in the fluorescence intensity (ΔG) was calculated by comparing mean grayscale levels between sound and worn areas. Finally, histological examination was conducted by stereomicroscope to confirm the presence of dentine exposure. Results: 100 teeth were included in the final analysis without six teeth having enamel cracks around worn area. The ΔG values increased with the severity of TW as quantified using conventional TWI codes, and differed significantly between the sound and enamel- and dentine-wear teeth (P<0.001). The histology indicated that enamel remained on 57 teeth, while 43 teeth had dentine-exposed wear and showed significant differences in ΔG compared with enamel-remained teeth. Conclusions: The fluorescence intensity differed significantly depending on the presence of dentine exposure. ΔG could be used to distinguish between sound and enamel- and dentine-wear teeth with a significant correlation. These findings indicate that QLF could be useful for determining the severity of TW of occlusal surfaces noninvasively.
关键词： tooth wear index (TWI),fluorescence intensity,tooth wear,quantitative light-induced fluorescence (QLF),occlusal wear
更新于2025-09-23 15:22:29
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Optical thermometry through infrared excited green upconversion of KLa(MoO4)2:Yb3+/Er3+ Phosphor
摘要： A series of KLa(MoO4)2:Yb3+/Er3+ phosphor was synthesized by a simple hydrothermal method. Under the excitation of 980 nm laser, the phosphor show intense green bands peaked at 525 and 550 nm and a negligible 658 nm red emission (4F9/2→4I15/2), respectively. The optical temperature sensing properties of the phosphor through the fluorescence intensity ratio (FIR) method were discussed by analyzing intensities ratio of 2H11/2 and 4S3/2 emission around the range of 303–423 K. The maximum sensor sensitivity derived from the FIR of the upconversion(UC) green emissions was approximately 0.0105 K-1. This indicates that the phosphor can be used as an excellent material for optical temperature sensing.
关键词： fluorescence intensity ratio,upconversion,optical temperature sensing
更新于2025-09-23 15:21:01
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A method for the statistical evaluation of the fluorescence intensity of single blinking quantum dots using a confocal fluorescence microscope
摘要： The evaluation of the fluorescence intensity of single quantum dots (QDs) using a confocal fluorescence microscope can provide an alternative approach for estimating the effects of environmental changes or surface modifications on the fluorescence intensity of single QDs. In the case of blinking QDs, irregular blinking would significantly influence the intensity evaluation results that are based on the analysis of one or a few single QDs. In this regard, statistical intensity evaluations based on a large number of single QDs would be helpful to estimate an approximate intensity value of single QDs with reduced effects of blinking on the evaluation results. Herein, we developed a convenient method to statistically evaluate the fluorescence intensity of a large number of single blinking QDs using Gaussian distribution. Based on the intensity analysis of thousands of single QDs, the fluorescence intensity of the single QDs evaluated using a confocal fluorescence microscope was approximately 4090 with little data fluctuation induced by blinking.
关键词： confocal fluorescence microscope,statistical evaluation,fluorescence intensity,single blinking quantum dots,Gaussian distribution
更新于2025-09-23 15:19:57
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Temperature dependence of the parameters of laser-induced fluorescence and species composition of phytoplankton: The theory and the experiments
摘要： The article discusses the opportunity to determine the species composition of a mixture of microalgae by using the temperature dependence of their laser-induced fluorescence (LIF). Experimental temperature dependences of fluorescence were obtained for the following microalgae: Picochlorum maculatum, Dunaliella salina, Chlorella minutissima, Tetraselmis viridis, Porphyridium purpureum, and Rhodomonas salina. It has been shown that the temperature dependence of fluorescence intensity of chlorophyll a in microalgae is reflective of the specific processes in cells of different microalgae species. A mathematical model for the temperature dependence of microalgae fluorescence and its relationship with the processes occurring in microalgae cells when heated has been formulated. The model allows determining the composition of mixtures with sufficient accuracy, as was shown experimentally on test mixtures of microalgae cultures.
关键词： Temperature dependence of fluorescence intensity,Phytoplankton,Chlorophyll a,Laser-induced fluorescence
更新于2025-09-16 10:30:52
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Highly sensitive optical thermometers based on unconventional thermometric coupled levels of Tm <sup>3+</sup> following a Boltzmann-type distribution in oxyfluoride glass ceramics
摘要： Oxyfluoride glass ceramics (GCs) containing b-PbF2 nanocrystals (NCs) doped with Tm3+ and Yb3+ were synthesized by a conventional melt-quenching method and a subsequent glass crystallization route. In b-PbF2:Tm3+/Yb3+ GCs, Tm3+/Yb3+ is surrounded by fluoride with a low phonon energy, ensuring its intense emissions at 362 (1D2 - 3H6), 450 (1D2 - 3F4), 478 (1G4 - 3H6), 648 (1G4 - 3F4), 700 (3F2,3 - 3H6) and 800 (3H4 - 3H6) nm excited by 976 nm laser. Furthermore, temperature-dependent upconversion luminescence (UCL) behaviors of b-PbF2:Tm3+/Yb3+ GCs were systematically investigated to explore the thermometric performance with the assistance of the fluorescence intensity ratio (FIR) method by employing conventional TCELs of 3F2,3/3H4 following a Boltzmann distribution and two unconventional coupled levels of 3F2,3/1D2 and 3F2,3/1G4 governed by a Boltzmann-type distribution. Impressively, the relative sensitivity (Sr) of 3F2,3/1D2 states (I700nm/I362nm), 3F2,3/1G4 states (I700nm/I478nm), and 3F2,3/3H4 states (I700nm/I800nm) was obtained in this work as values of 1.30% K-1, 1.38% K-1, and 0.87% K-1, respectively. Compared with the conventional TCELs of 3F2,3/3H4, the two unconventional coupled levels of 3F2,3/1D2 and 3F2,3/1G4 present preferable properties as temperature probes enabling optical ratiometric thermometers. The research in this work provides an important advance in exploring other innovative FIR methods for optical thermometers to enable an intense and precise probing signal and detect temperature accurately.
关键词： fluorescence intensity ratio,Yb3+,oxyfluoride glass ceramics,Tm3+,Boltzmann-type distribution,optical thermometers
更新于2025-09-16 10:30:52
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Constructing new thermally coupled levels based on different emitting centers for high sensitive optical thermometer
摘要： In multi-emitting and thermochromic Bi3+-Tb3+-Eu3+ co-doped garnet type Ca3Sc2Si3O12 phosphor, new thermally coupled levels (New-TCLs) are firstly constructed based on 3P1(Bi3+)/5D0(Eu3+) and 5D4(Tb3+)/5D0(Eu3+). And the relative electron population of New-TCLs obeys similar Boltzmann type distribution rules owing to stronger thermalization process with the increase of temperature, which can be elaborated by steady-state rate equations. Hence, a novel self-calibrated non-invasion optical thermometer with high absolute/relative temperature sensitivities (0.094 K?1 at 498 K; 1.0% K?1 at 448 K) and good signal discrimination (Δλ ≈ 158 nm) can be achieved by taking advantage of fluorescence intensity ratio of such New-TCLs. This work exhibits a novel strategy to design high-performance optical thermometer in high temperature environment.
关键词： New thermally coupled levels,Thermalization,Optical thermometer,Fluorescence intensity ratio
更新于2025-09-12 10:27:22
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Fluorescence detection of Escherichia coli on mannose modified ZnTe quantum dots
摘要： Rapid detection and identification of Escherichia coli (E.coli) is essential to prevent its quickly spread. In this study, a novel fluorescence probe based on ZnTe quantum dots (QDs) modified by mannose (MAN) had been prepared for the determination of E.coli. The results showed that the obtained QDs showed excellent selectivity toward E.coli, and presented a good linearity in range of 1.0 × 105~1.0 × 108 CFU/mL. The optimum fluorescence intensity for detecting E.coli was found to be at pH 7.0 with a temperature of 25 oC and incubation time of 20 min. Under these optimum conditions, the detection limit of E.coli was 4.6 × 104 CFU/mL. The quenching was discussed to be a static quenching procedure, which was proved by the quenching efficiency of QDs decreased with the temperature increasing.
关键词： Fluorescence intensity,Mannose,ZnTe quantum dots,Probe,Escherichia coli
更新于2025-09-11 14:15:04
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Optical investigation of Er3+ and Er3+/Yb3+ doped zinc-tellurite glass for solid-state lighting and optical thermometry
摘要： Er3+ and Er3+/Yb3+ doped zinc tellurite (ZnO/TeO2) glasses were prepared using melt quenching technique. Spectroscopic properties of the glasses were studied by absorption spectroscopy, luminescence spectroscopy, and color chromaticity coordinates (CIE-1931) measurements. Upconverted-emission intensities and the CIE-1931 coordinates were strongly affected by the presence of Yb3+ ion, as well as the excitation power density of 975 nm laser light. Effect of temperature on green upconverted-emissions from two thermally coupled 2H11/2 and 4S3/2 levels of Er3+ ions were measured and fluorescence intensity ratio technique was applied to investigate the temperature sensing properties. High sensitivity and short response time properties make ZnO/TeO2 glasses a very good candidate for non-contact optical temperature sensor applications. The maximum sensitivity of the glasses doped with Er3+ and Er3+/Yb3+ were found to be 72×10-4 K-1 and 120×10-4 K-1 at 429 K, respectively which are much higher than previously reported temperature sensors based on Er3+ ion doped materials. Hence, Er3+/Yb3+ doped zinc-tellurite glass can be more suitable than that of doped with Er3+ ions only for color tunable solid-state lighting and non-contact optical thermometry applications.
关键词： Solid-state lighting,non-contact optical thermometry,fluorescence intensity ratio (FIR),zinc-tellurite glass,upconversion
更新于2025-09-09 09:28:46