Investigation of photodarkening in Yb-doped fibers with fluorescence spectra

2021 ◽  
Author(s):  
Ji Won Kim ◽  
J. S. Park ◽  
E. J. Park ◽  
Y. J. Oh ◽  
Hoon Jeong
Keyword(s):  
Fluorescence Spectra ◽  
Doped Fibers

Raman And Fluorescence Spectra Observed in Laser Microprobe Measurements of Several Compositions in the Ln-Ba-Cu-O System

1990 ◽  
Vol 48 (2) ◽  
pp. 278-279
Author(s):  
Edgar S. Etz ◽  
Thomas D. Schroeder ◽  
Winnie Wong-Ng
Keyword(s):  
Fluorescence Spectra ◽  
Single Phase ◽  
X Ray Diffraction ◽  
Ceramic Powders ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
Raman Microprobe ◽  
Methods Of Synthesis ◽  
Compositional Homogeneity ◽  
Processing Techniques

We are investigating by Raman microprobe measurements the superconducting and related phases in the LnBa2Cu3O7-x (for x=0 to 1) system where yttrium has been replaced by several of the lanthanide (Ln = Nd,Sm,Eu,Ho,Er) elements. The aim is to relate the observed optical spectra (Raman and fluorescence) to the compositional and structural properties of these solids as part of comprehensive materials characterization. The results are correlated with the methods of synthesis, the processing techniques of these materials, and their superconducting properties. Of relevance is the substitutional chemistry of these isostructural systems, the differences in the spectra, and their microanalytical usefulness for the detection of impurity phases, and the assessment of compositional homogeneity. The Raman spectra of most of these compounds are well understood from accounts in the literature.The materials examined here are mostly ceramic powders prepared by conventional solid state reaction techniques. The bulk samples are of nominally single-phase composition as determined by x-ray diffraction.

Fluorescence of BODIPY Dyes in Gas Phase at near Ambient Conditions

2020 ◽  
Author(s):  
Kseniya A. Mariewskaya ◽  
Denis Larkin ◽  
Yuri Samoilichenko ◽  
Vladimir Korshun ◽  
Alex Ustinov
Keyword(s):  
Gas Phase ◽  
Molecular Interactions ◽  
Atmospheric Pressure ◽  
Fluorescence Spectra ◽  
Visible Range ◽  
Intrinsic Properties ◽  
Ambient Conditions ◽  
Ideal Model ◽  
Molecular Fluorescence ◽  
Tesla Coil

Molecular fluorescence is a phenomenon that is usually observed in condensed phase. It is strongly affected by molecular interactions. The study of fluorescence spectra in the gas phase can provide a nearly-ideal model for the evaluation of intrinsic properties of the fluorophores. Unfortunately, most conventional fluorophores are not volatile enough to allow study of their fluorescence in the gas phase. Here we report very bright gas phase fluorescence of simple BODIPY dyes that can be readily observed at atmospheric pressure using conventional fluorescence instrumentation. To our knowledge, this is the first example of visible range gas phase fluorescence at near ambient conditions. Evaporation of the dye in vacuum allowed us to demonstrate organic molecular electroluminescence in gas discharge excited by electric field produced by a Tesla coil.

Biochemical study of fibrinolytic protease from Euphausia superba possessing multifunctional serine protease activity

2020 ◽  
Vol 27 ◽  
Author(s):  
Guo-Ying Qian ◽  
Gyutae Lim ◽  
Shang-Jun Yin ◽  
Jun-Mo Yang ◽  
Jinhyuk Lee ◽  
...  
Keyword(s):  
Defense Mechanisms ◽  
Fluorescence Spectra ◽  
Biochemical Study ◽  
Euphausia Superba ◽  
Md Simulations ◽  
Time Interval ◽  
Serine Residue ◽  
Catalytic Function ◽  
Serine Protease Activity ◽  
Key Residues

Background: Background: Fibrinolytic protease from Euphausia superba (EFP) was isolated. Objective: Biochemical distinctions, regulation of the catalytic function, and the key residues of EFP were investigated. Methods: The serial inhibition kinetic evaluations coupled with measurements of fluorescence spectra in the presence of 4- (2-aminoethyl) benzene sulfonyl fluoride hydrochloride (AEBSF) was conducted. The computational molecular dynamics (MD) simulations were also applied for a comparative study. Results: The enzyme behaved as a monomeric protein with a molecular mass of about 28.6 kD with Km BApNA = 0.629 ± 0.02 mM and kcat/Km BApNA = 7.08 s-1 /mM. The real-time interval measurements revealed that the inactivation was a first-order reaction, with the kinetic processes shifting from a monophase to a biphase. Measurements of fluorescence spectra showed that serine residue modification by AEBSF directly caused conspicuous changes of the tertiary structures and exposed hydrophobic surfaces. Some osmolytes were applied to find protective roles. These results confirmed that the active region of EFP is more flexible than the overall enzyme molecule and serine, as the key residue, is associated with the regional unfolding of EFP in addition to its catalytic role. The MD simulations were supportive to the kinetics data. Conclusion: Our study indicated that EFP has an essential serine residue for its catalyst function and associated folding behaviors. Also, the functional role of osmolytes such as proline and glycine that may play a role in defense mechanisms from environmental adaptation in a krill’s body was suggested.

Luminescent Properties of Gd2MoO6:Eu3+ Nanophosphor for WLEDs

2021 ◽  
Author(s):  
Yan Chen ◽  
Yuemei Lan ◽  
Dong Wang ◽  
Guoxing Zhang ◽  
Wenlong Peng ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Fluorescence Spectra ◽  
Solvothermal Method ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

A series of Gd2-xMoO6:xEu3+(x=0.18-0.38) nanophosphors were synthesized by the solvothermal method. The properties of this nanophosphor were characterized by x-ray diffraction (XRD), transmission electron microscope (TEM), fluorescence spectra and diffuse...

scholarly journals Green Synthesis of Multifunctional Carbon Dots with Antibacterial Activities

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 369 ◽  
Author(s):  
Arumugam Saravanan ◽  
Moorthy Maruthapandi ◽  
Poushali Das ◽  
John H. T. Luong ◽  
Aharon Gedanken
Keyword(s):  
Carbon Dots ◽  
Fluorescence Spectra ◽  
Antibacterial Effect ◽  
Curcuma Longa ◽  
Antibacterial Activities ◽  
Blue Color ◽  
Mean Size ◽  
One Step ◽  
Bactericidal Activities ◽  
Bright Blue

Carbon dots (CDs) were obtained from medicinal turmeric leaves (Curcuma longa) by a facile one-step hydrothermal method and evaluated for their bactericidal activities against two gram-negative; Escherichia coli, Klebsiella pneumoniae, and two gram-positive counterparts; Staphylococcus aureus, S. epidermidis. The CDs exhibited spherical shapes with a mean size of 2.6 nm. The fluorescence spectra of CDs revealed intense fluorescence at λex/em = 362/429 nm with a bright blue color in an aqueous solution. The CDs showed strong photostability under various environmental conditions (pH, salt, and UV-radiation). The complete bactericidal potency of CDs was 0.25 mg/mL for E.coli and S. aureus after 8 h of exposure, while for K. pneumoniae, and S. epidermidis, the CDs at 0.5 mg/mL good antibacterial effect within 8 h and complete eradication after 24 h of exposure is observed. The release of reactive oxygen species played a crucial role in the death of the bacterial cell. The present study provides a strategy for the preparation of CDs from a medicinal plant and their potential antibacterial activities against four common contagious pathogens.

scholarly journals Ultrafast Electron/Energy Transfer and Intersystem Crossing Mechanisms in BODIPY-Porphyrin Compounds

Processes ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 312
Author(s):  
Yusuf Tutel ◽  
Gökhan Sevinç ◽  
Betül Küçüköz ◽  
Elif Akhuseyin Yildiz ◽  
Ahmet Karatay ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Fluorescence Spectra ◽  
Visible Region ◽  
Energy Transfer Mechanism ◽  
Free Base ◽  
Pump Probe ◽  
Harvesting Efficiency ◽  
Probe Spectroscopy ◽  
Absorption Features ◽  
Transfer Mechanisms

Meso-substituted borondipyrromethene (BODIPY)-porphyrin compounds that include free base porphyrin with two different numbers of BODIPY groups (BDP-TTP and 3BDP-TTP) were designed and synthesized to analyze intramolecular energy transfer mechanisms of meso-substituted BODIPY-porphyrin dyads and the effect of the different numbers of BODIPY groups connected to free-base porphyrin on the energy transfer mechanism. Absorption spectra of BODIPY-porphyrin conjugates showed wide absorption features in the visible region, and that is highly valuable to increase light-harvesting efficiency. Fluorescence spectra of the studied compounds proved that BODIPY emission intensity decreased upon the photoexcitation of the BODIPY core, due to the energy transfer from BODIPY unit to porphyrin. In addition, ultrafast pump-probe spectroscopy measurements indicated that the energy transfer of the 3BDP-TTP compound (about 3 ps) is faster than the BDP-TTP compound (about 22 ps). Since the BODIPY core directly binds to the porphyrin unit, rapid energy transfer was seen for both compounds. Thus, the energy transfer rate increased with an increasing number of BODIPY moiety connected to free-base porphyrin.

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