scholarly journals Smart Mn7+ Sensing via Quenching on Dual Fluorescence of Eu3+ Complex-Modified TiO2 Nanoparticles

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3283
Author(s):  
Wenbin Yang ◽  
Siqi Niu ◽  
Yao Wang ◽  
Linjun Huang ◽  
Shichao Wang ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Fluorescence Intensity ◽  
Solvothermal Method ◽  
Structural Deformation ◽  
Fluorescence Intensity Ratio ◽  
Dual Fluorescence ◽  
Red Emission ◽  
Sensing System ◽  
Uv Visible ◽  
Uv Excitation

In this work, titania (TiO2) nanoparticles modified by Eu(TTA)3Phen complexes (ETP) were prepared by a simple solvothermal method developing a fluorescence Mn7+ pollutant sensing system. The characterization results indicate that the ETP cause structural deformation and redshifts of the UV-visible light absorptions of host TiO2 nanoparticles. The ETP also reduce the crystallinity and crystallite size of TiO2 nanoparticles. Compared with TiO2 nanoparticles modified with Eu3+ (TiO2-Eu3+), TiO2 nanoparticles modified with ETP (TiO2-ETP) exhibit significantly stronger photoluminescence under the excitation of 394 nm. Under UV excitation, TiO2-ETP nanoparticles showed blue and red emission corresponding to TiO2 and Eu3+. In addition, as the concentration of ETP in TiO2 nanoparticles increases, the PL intensity at 612 nm also increases. When ETP-modified TiO2 nanoparticles are added to an aqueous solution containing Mn7+, the fluorescence intensity of both TiO2 and ETP decreases. The evolution of the fluorescence intensity ratio (I1/I2) of TiO2 and ETP is linearly related to the concentration of Mn7+. The sensitivity of fluorescence intensity to Mn7+ concentration enables the design of dual fluorescence ratio solid particle sensors. The method proposed here is simple, accurate, efficient, and not affected by the environmental conditions.

scholarly journals Nd3+-Doped TiO2 Nanoparticles as Nanothermometer: High Sensitivity in Temperature Evaluation inside Biological Windows

Sensors ◽  
2021 ◽  
Vol 21 (16) ◽  
pp. 5306
Author(s):  
Selene Acosta ◽  
Luis J. Borrero-González ◽  
Polona Umek ◽  
Luiz A. O. Nunes ◽  
Peter Guttmann ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Fluorescence Intensity ◽  
Emission Intensity ◽  
Intensity Ratio ◽  
Potential Temperature ◽  
Broad Band ◽  
Relative Sensitivity ◽  
Effect Of Temperature ◽  
Fluorescence Intensity Ratio ◽  
Photoluminescence Intensity

TiO2 nanoparticles doped with different amounts of Nd3+ (0.5, 1, and 3 wt.%) were synthetized by the sol–gel method, and evaluated as potential temperature nanoprobes using the fluorescence intensity ratio between thermal-sensitive radiative transitions of the Nd3+. XRD characterization identified the anatase phase in all the doped samples. The morphology of the nanoparticles was observed with SEM, TEM and HRTEM microscopies. The relative amount of Nd3+ in TiO2 was obtained by EDXS, and the oxidation state of titanium and neodymium was investigated via XPS and NEXAFS, respectively. Nd3+ was present in all the samples, unlike titanium, where besides Ti4+, a significantly amount of Ti3+ was observed; the relative concentration of Ti3+ increased as the amount of Nd3+ in the TiO2 nanoparticles increased. The photoluminescence of the synthetized nanoparticles was investigated, with excitation wavelengths of 350, 514 and 600 nm. The emission intensity of the broad band that was associated with the presence of defects in the TiO2, increased when the concentration of Nd3+ was increased. Using 600 nm for excitation, the 4F7/2→4I9/2, 4F5/2→4I9/2 and 4F3/2→4I9/2 transitions of Nd3+ ions, centered at 760 nm, 821 nm, and 880 nm, respectively, were observed. Finally, the effect of temperature in the photoluminescence intensity of the synthetized nanoparticles was investigated, with an excitation wavelength of 600 nm. The spectra were collected in the 288–348 K range. For increasing temperatures, the emission intensity of the 4F7/2→4I9/2 and 4F5/2→4I9/2 transitions increased significantly, in contrast to the 4F3/2→4I9/2 transition, in which the intensity emission decreased. The fluorescence intensity ratio between the transitions I821I880=F5/24I49/2F43/2I49/2 and I760I880=F47/2I49/2F43/2I49/2 were used to calculate the relative sensitivity of the sensors. The relative sensitivity was near 3% K−1 for I760I880 and near 1% K−1 for I821I880.

scholarly journals Effect of SiO2 and TiO2 Nanoparticles on the Performance of UV Visible Fluorescent Coatings

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 928
Author(s):  
Sanja Mahović Poljaček ◽  
Tamara Tomašegović ◽  
Mirjam Leskovšek ◽  
Urška Stanković Elesini
Keyword(s):  
Tio2 Nanoparticles ◽  
Degradation Process ◽  
Bending Stiffness ◽  
Attenuated Total Reflection ◽  
Surface Coatings ◽  
Accelerated Ageing ◽  
Sem Images ◽  
Structural Surface ◽  
Uv Visible ◽  
Reflectance Measurements

In the present research, the properties of ultraviolet (UV) visible (daylight invisible) fluorescent coatings modified by the addition of SiO2 and TiO2 nanoparticles were studied. Structural, surface, and mechanical properties and changes in the coatings caused by accelerated ageing were analyzed. The results showed that the addition of nanoparticles caused the changes in unaged and aged printed coatings. Reflectance measurements of modified coatings showed that addition of TiO2 nanoparticles improved the visual effect of the unaged coatings. Furthermore, results have shown that the addition of SiO2 did not diminish the reflectance of the modified coatings after ageing. The results of roughness measurements showed that the addition of SiO2 decreased roughness after the ageing process, probably due to the degradation process indicated by Attenuated Total Reflection Fourier Transform Infrared (ATR-FTIR) spectroscopy. The roughness of the coatings with TiO2 nanoparticles was increased after the ageing on the samples with higher concentrations of TiO2 due to the agglomerates of plastisol formed on the surface of the coatings, visible in SEM images. Surface analysis of coatings showed that TiO2 caused an increase in the polarity of the surface coatings. Results of the bending stiffness showed that the addition of the nanoparticles to the coating, especially of SiO2, significantly improved the bending stiffness of the unaged samples.

Strain-independent temperature measurement by use of a fluorescence intensity ratio technique in optical fiber

2000 ◽  
Vol 39 (18) ◽  
pp. 3050 ◽  
Author(s):  
Scott A. Wade ◽  
Stephen F. Collins ◽  
Kenneth T. V. Grattan ◽  
Gregory W. Baxter
Keyword(s):  
Optical Fiber ◽  
Temperature Measurement ◽  
Fluorescence Intensity ◽  
Intensity Ratio ◽  
Fluorescence Intensity Ratio

scholarly journals Excitation-Independent Emission of Carbon Quantum Dot Solids

2020 ◽  
Vol 2020 ◽  
pp. 1-5
Author(s):  
Xuan-Dung Mai ◽  
Yen Thi Hai Phan ◽  
Van-Quang Nguyen
Keyword(s):  
Solid State ◽  
Solvothermal Method ◽  
Blue Emission ◽  
Carbon Quantum Dots ◽  
Solid State Lighting ◽  
Optical And Electrical Properties ◽  
Red Emission ◽  
Solid Films ◽  
Carbon Quantum Dot ◽  
S States

Solid assemblies of carbon quantum dots (CQDs) are important for diverse applications including LEDs, solar cells, and photosensors; their optical and electrical properties have not been explored yet. Herein, we used amphiphilic CQDs synthesized from citric acid and thiourea by a solvothermal method to fabricate CQD solid films. Optical properties of CQDs studied by UV-Vis and photoluminescence spectroscopies indicate that CQDs possess three different emission centers at 425 nm, 525 nm, and 625 nm originating from C sp2 states, N-states, and S-states, respectively. In a solid state, π-π stacking quenched the blue emission, while the red emission increased. Importantly, CQD films exhibited excitation independence, which is important to design solid-state lighting applications.

scholarly journals Detecting Variable Resistance by Fluorescence Intensity Ratio Technology

Sensors ◽  
2019 ◽  
Vol 19 (10) ◽  
pp. 2400 ◽  
Author(s):  
Wanjun Sheng ◽  
Xiangfu Wang ◽  
Yong Tao ◽  
Xiaohong Yan
Keyword(s):  
Fluorescence Intensity ◽  
Intensity Ratio ◽  
Negative Temperature ◽  
Relative Sensitivity ◽  
New Method ◽  
Fluorescence Intensity Ratio ◽  
Time Intervals ◽  
Variable Resistance ◽  
Reduced Graphene ◽  
Short Time

We report a new method for detecting variable resistance during short time intervals by using an optical method. A novel variable-resistance sensor composed of up-conversion nanoparticles (NaYF4:Yb3+,Er3+) and reduced graphene oxide (RGO) is designed based on characteristics of a negative temperature coefficient (NTC) resistive element. The fluorescence intensity ratio (FIR) technology based on green and red emissions is used to detect variable resistance. Combining the Boltzmann distributing law with Steinhart–Hart equation, the FIR and relative sensitivity SR as a function of resistance can be defined. The maximum value of SR is 1.039 × 10−3/Ω. This work reports a new method for measuring variable resistance based on the experimental data from fluorescence spectrum.

Preparation of fusiform Ti3+ self-doped TiO2 nanoparticles by mixed solvothermal method and its photoelectrochemical properties

2019 ◽  
Vol 252 ◽  
pp. 134-137
Author(s):  
Yadong Song ◽  
Bei Li ◽  
Yanying Shi ◽  
Qingyao Wang ◽  
Rencheng Jin ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Solvothermal Method ◽  
Photoelectrochemical Properties ◽  
Doped Tio2
Sign in / Sign up

Export Citation Format

Share Document