scholarly journals Comparative structural and optical spectroscopic studies of Nd3+ ion doped LaF3 and their core/shell nanoparticles

2018 ◽  
Vol 12 (1) ◽  
pp. 78-85
Author(s):  
Anees Ansari ◽  
Joselito Labis ◽  
Mohamed Manthrammel
Keyword(s):  
Surface Coating ◽  
Silica Surface ◽  
Uv Light ◽  
Emission Spectra ◽  
Spectroscopic Studies ◽  
Hexagonal Structure ◽  
Spectral Studies ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Average Grain Size

LaF3 :Nd3+ (core), LaF3 :Nd3+@LaF3 (core/shell) and LaF3 :Nd3+@LaF3@SiO2 (core/shell/SiO2) nanoparticles (NPs) were designed and synthesized at low temperature. The structure and morphology of the as-prepared nanoproducts were characterized by X-ray diffraction and transmission electron microscopy (TEM) techniques. Thermal analysis and FTIR spectral studies were conducted to examine the surface properties of the nanomaterials. The as-prepared LaF3 :Nd3+ NPs exhibited hexagonal structure and were composed of monodispersed irregularly and spherically shaped NPs with average grain size of 21 nm. TEM image showed the successful silica surface coating, which was verified by FTIR spectral analysis. The emission spectra of LaF3 :Nd3+ NPs was obtained by monitoring the emission of Nd3+ at 325 nm (Cd laser) where it exhibited the characteristic 4f?4f transitions lines originating from the Nd 4f3 configuration. Under UV light irradiation, the emission spectra revealed various strong emission transitions which were greatly affected by the surrounding silica surface coating. These observed results suggested future applications in biolabeling and light-emitting diode.

scholarly journals Spectroscopic studies on Tb3+ binding to S-100a protein

1987 ◽  
Vol 244 (3) ◽  
pp. 559-563 ◽  
Author(s):  
R S Mani ◽  
C M Kay
Keyword(s):  
Conformational Changes ◽  
Binding Assay ◽  
Emission Spectra ◽  
Spectroscopic Studies ◽  
Spectral Studies ◽  
Difference Spectroscopy ◽  
Fluorescence Excitation ◽  
Fluorescence Studies ◽  
Helical Content ◽  
Direct Binding

Direct binding assay and fluorescence studies revealed that S-100a protein binds 2 mol of Tb3+/mol of protein at pH 6.6. The protein binds Tb3+ much more tightly than Ca2+, and the upper limit of the observed Kd value for Tb3+ is 3.5 × 10(-6) M. The Tb3+-binding site on the protein must be close to a tyrosine residue, as indicated by fluorescence excitation and emission spectra, where energy transfer from tyrosine is noted. Addition of Tb3+ resulted in a conformational change in the protein, as revealed by u.v.-difference spectroscopy and c.d. studies. Far-u.v. c.d. studies indicated the helical content to decrease from approx. 39% to 35% in the presence of Tb3+. From u.v.-difference-spectroscopy results the single tryptophan and the tyrosine chromophores in S-100a protein are blue-shifted (i.e. exposed to the solvent) in the presence of Tb3+ and the observed conformational changes are similar to those induced by Ca2+, suggesting that Tb3+ can be employed as a Ca2+ analogue in spectral studies with S-100a protein.

Spherical SiO2 @ GdPO4 : Eu3+ Core–Shell Phosphors: Sol–Gel Synthesis and Characterization

2007 ◽  
Vol 7 (2) ◽  
pp. 542-548 ◽  
Author(s):  
Cuikun Lin ◽  
Bo Zhao ◽  
Zhenling Wang ◽  
Min Yu ◽  
Huan Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Low Voltage ◽  
Uv Light ◽  
Sol Gel ◽  
Emission Spectra ◽  
Core Shell ◽  
Time Resolved ◽  
Potential Applications ◽  
Ft Ir ◽  
Red Luminescence

Nanocrystalline GdPO4 : Eu3+ phosphor layers were coated on non-aggregated, monodisperse and spherical SiO2 particles by Pechini sol–gel method, resulting in the formation of core–shell structured SiO2 @ GdPO4 : Eu3+ particles. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL), low-voltage cathodoluminescence (CL), time-resolved PL spectra and lifetimes were used to characterize the core–shell structured materials. Both XRD and FT-IR results indicate that GdPO4 layers have been successfully coated on the SiO2 particles, which can be further verified by the images of FESEM and TEM. Under UV light excitation, the SiO2 @ GdPO4 : Eu3+ phosphors show orange-red luminescence with Eu3+ 5D0–7F1 (593 nm) as the most prominent group. The PL excitation and emission spectra suggest that an energy transfer occurs from Gd3+ to Eu3+ in SiO2 @ GdPO4 : Eu3+ phosphors. The obtained core–shell phosphors have potential applications in FED and PDP devices.

scholarly journals Fabrication of Magnetite/Silica/Titania Core-Shell Nanoparticles

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Suh Cem Pang ◽  
Sze Yun Kho ◽  
Suk Fun Chin
Keyword(s):  
Methylene Blue ◽  
Uv Light ◽  
Sol Gel ◽  
Core Shell ◽  
Silica Nanospheres ◽  
Shell Nanoparticles ◽  
Gel Method ◽  
Uv Light Irradiation ◽  
Silica Nanosphere ◽  
Core Shell Nanoparticles

Fe3O4/SiO2/TiO2core-shell nanoparticles were synthesized via a sol-gel method with the aid of sonication. Fe3O4nanoparticles were being encapsulated within discrete silica nanospheres, and a layer of TiO2shell was then coated directly onto each silica nanosphere. As-synthesized Fe3O4/SiO2/TiO2core-shell nanoparticles showed enhanced photocatalytic properties as evidenced by the enhanced photodegradation of methylene blue under UV light irradiation.

Spherical SiO2 @ GdPO4 : Eu3+ Core–Shell Phosphors: Sol–Gel Synthesis and Characterization

2007 ◽  
Vol 7 (2) ◽  
pp. 542-548
Author(s):  
Cuikun Lin ◽  
Bo Zhao ◽  
Zhenling Wang ◽  
Min Yu ◽  
Huan Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Low Voltage ◽  
Uv Light ◽  
Sol Gel ◽  
Emission Spectra ◽  
Core Shell ◽  
Time Resolved ◽  
Potential Applications ◽  
Ft Ir ◽  
Red Luminescence

Nanocrystalline GdPO4 : Eu3+ phosphor layers were coated on non-aggregated, monodisperse and spherical SiO2 particles by Pechini sol–gel method, resulting in the formation of core–shell structured SiO2 @ GdPO4 : Eu3+ particles. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), photoluminescence (PL), low-voltage cathodoluminescence (CL), time-resolved PL spectra and lifetimes were used to characterize the core–shell structured materials. Both XRD and FT-IR results indicate that GdPO4 layers have been successfully coated on the SiO2 particles, which can be further verified by the images of FESEM and TEM. Under UV light excitation, the SiO2 @ GdPO4 : Eu3+ phosphors show orange-red luminescence with Eu3+ 5D0–7F1 (593 nm) as the most prominent group. The PL excitation and emission spectra suggest that an energy transfer occurs from Gd3+ to Eu3+ in SiO2 @ GdPO4 : Eu3+ phosphors. The obtained core–shell phosphors have potential applications in FED and PDP devices.

scholarly journals Structural and Spectroscopic Characterization of PM 597 Dye-Silica Core-Shell Nanoparticles

2015 ◽  
Vol 2015 ◽  
pp. 1-7
Author(s):  
Tahani R. Al-Biladi ◽  
A. S. Al Dwayyan ◽  
M. Naziruddin Khan ◽  
Saif M. H. Qaid ◽  
Khalid Al Zahrani
Keyword(s):  
Emission Spectra ◽  
Spectroscopic Characterization ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Silica Core ◽  
Shell Particles ◽  
Average Size ◽  
Core Shell Nanoparticles ◽  
20 Nm

Nanostructured fluorescent pyrromethene (PM) doped-silica core-shell particles were successfully prepared by Stöber process. The average size of the particles was in the range of 10–20 nm measured by TEM micrograph. The atomic structure and morphology of PM 597/SiO2core/shell nanoparticles were studied by AFM and SEM, respectively. Absorption and emission spectra of the PM 597/SiO2core/shell nanoparticles under the UV irradiation were studied and not significantly influenced at the position of peaks. Finally, amplified spontaneous emission (ASE) and photobleaching of dye were examined and found no significant influence on the peaks of PM dye due to the formation of smaller sizes of PM 597/SiO2core/shell nanoparticles. The observed PM 597/SiO2core/shell nanoparticles were different in shapes with smaller size distribution and highly luminescent. Majority of nanoparticles were roughly spherical with many of them aggregated. The less photobleaching of dye core may be due to the protection of pumped energy by SiO2shell and restricts the leakage of dye.

The Effects of Surface Coating on the Structural and Magnetic Properties of CoAg Core-Shell Nanoparticles

2007 ◽  
Vol 43 (6) ◽  
pp. 3106-3108 ◽  
Author(s):  
Richard Evans ◽  
Florian Dorfbauer ◽  
Oleg Myrasov ◽  
Oksana Chubykalo-Fesenko ◽  
Thomas Schrefl ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Surface Coating ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Structural And Magnetic Properties ◽  
Core Shell Nanoparticles

scholarly journals The Influence of SiO2Shell on Fluorescent Properties of LaF3:Nd3+/SiO2Core/Shell Nanoparticles

2010 ◽  
Vol 2010 ◽  
pp. 1-5 ◽  
Author(s):  
Cui Kai ◽  
Gao Chao ◽  
Peng Bo ◽  
Wei Wei
Keyword(s):  
Fluorescence Intensity ◽  
Emission Spectra ◽  
Phonon Energy ◽  
Core Shell ◽  
Fluorescent Properties ◽  
Excitation Spectra ◽  
Shell Nanoparticles ◽  
Fluorescent Intensity ◽  
Different Temperatures ◽  
Core Shell Nanoparticles

Distinct effects of the SiO2shell on fluorescence properties of LaF3:Nd3+/SiO2core/shell nanoparticles were demonstrated by annealling the nanoparticles at different temperatures. Emission spectra, excitation spectra, and decay curves of the nanoparticles were measured. A significant improvement of fluorescence intensity was observed for LaF3:Nd3+/SiO2core/shell nanoparticles annealed at 900∘C. The phenomenon is ascribed to the change of environment of LaF3:Nd3+core which is imposed by SiO2shell. And the change is confirmed by the excitation spectra. It provides a useful way to improve fluorescent intensity of the SiO2-coated LaF3:Nd3+nanoparticles. The lifetime for nanoparticles annealed at 900∘Cshows a slight decrease contrast with nanoparticles annealed at 400 and 600∘C. This is caused by the higher phonon energy of SiO2than that of LaF3.

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