Influence of silver nanoparticles on absorption and fluorescence properties of laser dyes

2014 ◽  
Vol 92 (2) ◽  
pp. 163-167 ◽  
Author(s):  
H.R. Deepa ◽  
H.M. Suresh Kumar ◽  
M. Basanagouda ◽  
J. Thipperudrappa
Keyword(s):  
Silver Nanoparticles ◽  
Fluorescence Quenching ◽  
Room Temperature ◽  
Chemical Reduction ◽  
Mie Theory ◽  
Laser Dyes ◽  
Dynamic Quenching ◽  
Positive Deviation ◽  
Absorption And Fluorescence Spectroscopy ◽  
Quenching Process

The interaction of silver nanoparticles with four laser dyes, namely, LD-425, LD-489, LD-473, and LD-423, dispersed in methanol has been studied at room temperature by absorption and fluorescence spectroscopy. The silver nanoparticles were synthesized by chemical reduction and estimated size is 11 nm according to Mie theory. The changes in absorption spectrum of these dyes with the addition of silver nanoparticles suggest possible interaction with the silver nanoparticles. The magnitudes of the association constants are estimated using the Benesi–Hildebrand model. Fluorescence quenching has been observed for all the dyes with the addition of silver nanoparticles of different concentrations. The Stern–Volmer plots of fluorescence quenching in the case of LD-425 and LD-489 are found to be linear, suggesting the fluorescence quenching is because of the dynamic quenching process. But in the case of LD-473 and LD-423, the Stern–Volmer plots are nonlinear showing positive deviation and the fluorescence quenching in these dyes is because of static quenching processes. Also, it is found that the fluorescence quenching is not solely due to diffusion.

scholarly journals Fluorescence Quenching of DMB by Aniline in Benzene-Acetonitrile Mixture

2016 ◽  
Vol 65 ◽  
pp. 32-36 ◽  
Author(s):  
Ashok H. Sidarai ◽  
Vani R. Desai ◽  
Shirajahammad M. Hunagund ◽  
Mahantesha Basanagouda ◽  
Jagadish S. Kadadevarmath
Keyword(s):  
Fluorescence Quenching ◽  
Room Temperature ◽  
Solvent Mixture ◽  
Static Quenching ◽  
Solvent Mixtures ◽  
Dynamic Quenching ◽  
Approximation Model ◽  
Positive Deviation ◽  
Coumarin Dye ◽  
Static And Dynamic Quenching

The fluorescence quenching of coumarin dye namely 4-(2,6-dibromo-4-methyl-phenoxymethyl)-benzo[h]chromen-2-one [DMB] has been studied by aniline, in a different solvent mixture of benzene (BN) and acetonitrile (AN) at room temperature. The quenching is found to be appreciable and shows positive deviation from linearity in the Stern-Volmer (S-V) plots for all the solvent mixtures. The various rate parameters responsible for fluorescence quenching have been determined using a sphere of action static quenching model and finite sink approximation model. The magnitudes of these rate parameters indicate that positive deviation in the S-V plot is due to both static and dynamic quenching processes.

A study on fluorescence quenching of a laser dye by aromatic amines in alcohols

2015 ◽  
Vol 93 (4) ◽  
pp. 469-474 ◽  
Author(s):  
H.R. Deepa ◽  
J. Thipperudrappa ◽  
H.M. Suresh Kumar
Keyword(s):  
Fluorescence Quenching ◽  
Aromatic Amines ◽  
Room Temperature ◽  
Static Quenching ◽  
Laser Dye ◽  
Approximation Model ◽  
Positive Deviation ◽  
Quenching Rate ◽  
Time Resolved ◽  
Bimolecular Quenching

The fluorescence quenching of 1,2,3,8-tetrahydro-1,2,3,3,8-pentamethyl-5-(trifluoromethyl)-7H-pyrrolo[3,2-g]quinolin-7-one (LD-473) by aromatic amines, namely, aniline, dimethyl aniline, and diethyl aniline, in methanol, ethanol, propanol, and butanol has been studied at room temperature using steady-state and time-resolved methods. A positive deviation from linearity has been observed in Stern–Volmer (S–V) plots. Various quenching rate parameters have been determined using the extended S–V equation and are found to be dependent on the dielectric constant of alcohols. The quenching ability of amines increases with increasing their ionization energies. Further, with the use of the sphere of action, static quenching model, and finite sink approximation model, it is concluded that the bimolecular quenching reactions are due to the combined effect of both dynamic and static quenching processes.

scholarly journals Fabrication of Reduced Graphene Oxide-Ag Nanocomposites and Analysis on the Interaction with BSA

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Huali Zhang ◽  
Wen Liu ◽  
Linqing Yang ◽  
Jun Liu ◽  
Yunfei Wang ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Scanning Probe Microscopy ◽  
Chemical Reduction ◽  
Binding Reaction ◽  
Transmission Electron ◽  
Reduced Graphene ◽  
Quenching Process ◽  
Different Temperatures

Graphene is an excellent platform to support and stabilize silver nanoparticles (AgNPs). The reduced graphene oxide-silver nanoparticles (rGO-AgNPs) were synthesized by the chemical reduction method and characterized by using ultraviolet-visible (UV-vis) absorption, transmission electron microscopy (TEM), X-ray diffractometer (XRD), and scanning probe microscopy (SPM). The binding reaction of rGO-AgNPs with bovine serum albumin (BSA) was investigated by using fluorescence spectrometry and SPM. As the concentration of AgNPs increased, the fluorescence spectrum was quenched, and the quenching process of rGO-AgNPs and BSA was static quenching. Thermodynamic parameters of the absorption process were evaluated at different temperatures, and the negative values of Gibbs free energy (ΔG) showed that this process was spontaneous. The main type of interaction was hydrophobic interaction according to the values of changes in standard enthalpy (ΔH) and entropy (ΔS). In addition, the morphology changes of proteins interacting with nanomaterials were detected by SPM.

scholarly journals Synthesis and Comparative Antibacterial Activity of Fatty Acid Capped Silver Nanoparticles

2020 ◽  
Vol 14 (3) ◽  
pp. 1941-1947
Author(s):  
Rama Sharma
Keyword(s):  
Silver Nanoparticles ◽  
Antibacterial Activity ◽  
Fatty Acid ◽  
Room Temperature ◽  
Reduction Method ◽  
Chemical Reduction ◽  
Inert Atmosphere ◽  
Chemical Reduction Method ◽  
Visible Spectroscopy ◽  
E Coli

In the present work, the chemical reduction method has been used to synthesize silver nanoparticles using stearic acid capping agents in different concentrations. These nanoparticles are characterized by ultraviolet-visible spectroscopy and dynamic light scattering (DLS). The size of the synthesized silver nanoparticles found between 80-100 nm and stable up to 5 months. These nanoparticles show a very good bactericidal influence on E. coli and S. aureus. In this method silver nanoparticles have synthesized at room temperature without using any inert atmosphere, this is the advantage of this method over others.

scholarly journals Analysis of Fluorescence Quenching of BPBD by Aniline in Toluene

2013 ◽  
Vol 12 (1) ◽  
pp. 87-98
Author(s):  
J Thipperudrappa ◽  
S M Hanagodimath
Keyword(s):  
Steady State ◽  
Fluorescence Quenching ◽  
Room Temperature ◽  
Static Quenching ◽  
Approximation Model ◽  
Positive Deviation ◽  
Time Resolved Fluorescence ◽  
Time Resolved ◽  
Steady State Method ◽  
Volmer Plot

Fluorescence quenching of 2-(4'-t-Butylphenyl)-5-(4"-biphenylyl)-1,3,4-oxadiazole (BPBD) by aniline in toluene has been carried out at room temperature by steady state and time resolved fluorescence spectroscopy. The Stern-Volmer plot by steady state method has been found to be non-linear showing a positive deviation, whereas by time-resolved method it is linear. In order to interpret these results we have used the ground state complex and sphere of action static quenching models. Using these models various rate parameters have been determined. Based on these models, with finite sink approximation model, we conclude that positive deviation Stern-Volmer plot is due to the simultaneous presence of dynamic and static quenching processes.

Effect of solvent polarity on the fluorescence quenching of TMC molecule by aniline in benzene–acetonitrile mixtures

2016 ◽  
Vol 94 (11) ◽  
pp. 1125-1132 ◽  
Author(s):  
Ashok H. Sidarai ◽  
Vani R. Desai ◽  
Shirajahammad M. Hunagund ◽  
Mahantesha Basanagouda ◽  
Jagadish S. Kadadevarmath
Keyword(s):  
Fluorescence Quenching ◽  
Rate Constants ◽  
Transient State ◽  
Solvent Polarity ◽  
Coumarin Derivative ◽  
Solvent Mixtures ◽  
Positive Deviation ◽  
Diffusion Limited ◽  
Quenching Process ◽  
Volmer Plot

The fluorescence quenching of coumarin derivative, 6-methoxy-4-p-tolyloxymethyl-chromen-2-one by aniline is carried out in different solvent mixtures of benzene and acetonitrile at room temperature. The quenching is found to be appreciable and a positive deviation from linearity is observed in the Stern–Volmer plot in all the solvent mixtures. Various rate constants for fluorescence quenching processes have been estimated using a sphere of action static quenching model and a finite sink approximation model. From the positive deviation of linear Stern–Volmer plots and dependence of rate constants on the polarity of the solvents, it has been inferred that the quenching process is diffusion-limited, and static as well as dynamic quenching processes are responsible for the observed positive deviation in the Stern–Volmer plot. Further, both models have been found to agree well with transient state also in pure acetonitrile and benzene solvents.

Spectral Properties of Laser Dyes at varying Temperature

2020 ◽  
Author(s):  
H.R. Deepa ◽  
J. Thipperudrappa ◽  
H.M. Suresh Kumar
Keyword(s):  
Steady State ◽  
Fluorescence Lifetime ◽  
Fluorescence Intensity ◽  
Spectral Properties ◽  
Fluorescence Band ◽  
Laser Dyes ◽  
Dynamic Quenching ◽  
Positive Deviation ◽  
Quenching Effect ◽  
Transient Methods

Spectral properties of laser dyes 4-methyl-7-(4-morpholinyl)-2 H pyrano [2,3-b] pyridin-2-one (LD – 425) and 6,7,8,9-tetrahydro-6,8,9-trimethyl-4-(trifluoromrthyl)-2H-pyrano[2,3b][1,8]naphthyridin-2-one (LD – 489) have been investigated in the temperature range 250C - 650C by steady state and transient methods. Fluorescence intensity decreases with increase in temperature with fluorescence band maxima shifted towards shorter wavelength in both the dyes. Further, fluorescence lifetime has decreased with increase in temperature for LD - 425, whereas remained constant with change in temperature for LD - 489. The possible deactivation mechanisms are discussed. The quenching effect of these dyes in the presence of aniline at different temperature has been studied and the Stern-Volmer (S-V) plots are non-linear showing positive deviation. It has been observed that dynamic quenching constant increases with temperature, whereas static quenching constant is independent of temperature.

Improved Sol-Gel Materials for Efficient Solid State Dye Lasers

1993 ◽  
Vol 329 ◽  
Author(s):  
Michael Canva ◽  
Patrick Georges ◽  
Jean-Fran^ois Perelgritz ◽  
Alain Brun ◽  
Fréddric Chaput ◽  
...  
Keyword(s):  
Solid State ◽  
Physical Properties ◽  
Room Temperature ◽  
Sol Gel ◽  
Tunable Lasers ◽  
Optical Quality ◽  
Dye Lasers ◽  
Laser Dyes ◽  
Host Matrix ◽  
Host Matrices

AbstractPhotoresistant laser dyes were trapped in silica based xerogel host matrices to obtain solid state tunable lasers. For this purpose very dense xerogel samples with improved chemical and physical properties were prepared at room temperature by the sol-gel technology. The as-prepared materials were polished to obtain optical quality surfaces and were used as new lasing media.Lasing action of such different dyes as rhodamine, perylene and pyrromethene doping dense sol-gel matrices was demonstrated. Efficiencies of 30 % or lifetimes of more than 100,000 shots were achieved with different new ≤dye dopant/host matrix≥ couples. Their different performances are reviewed and discussed.

Room Temperature Alkali Metal Reduction of Carbon Dioxide

2020 ◽  
Author(s):  
Lucas A. Freeman ◽  
Akachukwu D. Obi ◽  
Haleigh R. Machost ◽  
Andrew Molino ◽  
Asa W. Nichols ◽  
...  
Keyword(s):  
Alkali Metal ◽  
Alkali Metals ◽  
Room Temperature ◽  
Chemical Reduction ◽  
Bond Cleavage ◽  
Open Shell ◽  
Metal Reduction ◽  
One Pot ◽  
Earth Abundant ◽  
Electron Reduction

The reduction of the relatively inert carbon–oxygen bonds of CO<sub>2</sub> to access useful CO<sub>2</sub>-derived organic products is one of the most important fundamental challenges in synthetic chemistry. Facilitating this bond-cleavage using earth-abundant, non-toxic main group elements (MGEs) is especially arduous because of the difficulty in achieving strong inner-sphere interactions between CO<sub>2</sub> and the MGE. Herein we report the first successful chemical reduction of CO<sub>2</sub> at room temperature by alkali metals, promoted by a cyclic(alkyl)(amino) carbene (CAAC). One-electron reduction of CAAC-CO<sub>2</sub> adduct (<b>1</b>) with lithium, sodium or potassium metal yields stable monoanionic radicals clusters [M(CAAC–CO<sub>2</sub>)]<sub>n</sub>(M = Li, Na, K, <b> 2</b>-<b>4</b>) and two-electron alkali metal reduction affords open-shell, dianionic clusters of the general formula [M<sub>2</sub>(CAAC–CO<sub>2</sub>)]<sub>n </sub>(<b>5</b>-<b>8</b>). It is notable that these crystalline clusters of reduced CO<sub>2</sub> may also be isolated via the “one-pot” reaction of free CO<sub>2</sub> with free CAAC followed by the addition of alkali metals – a reductive process which does not occur in the absence of carbene. Each of the products <b>2</b>-<b>8</b> were investigated using a combination of experimental and theoretical methods.<br>

Antimicrobial Activity of Silver Nanoparticles Prepared Under an Ultrasonic Field

2011 ◽  
Vol 4 (3) ◽  
pp. 1491-1496
Author(s):  
Umadevi M ◽  
Rani T ◽  
Balakrishnan T ◽  
Ramanibai R
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Silver Nanoparticles ◽  
Reduction Method ◽  
Therapeutic Potential ◽  
Chemical Reduction ◽  
Ultrasonic Field ◽  
Great Promise ◽  
Chemical Reduction Method ◽  
E Coli

Nanotechnology has great promise for improving the therapeutic potential of medicinal molecules and related agents. In this study, silver nanoparticles of different sizes were synthesized in an ultrasonic field using the chemical reduction method with sodium borohydride as a reducing agent. The size effect of silver nanoparticles on antimicrobial activity were tested against the microorganisms Staphylococcus aureus (MTCC No. 96), Bacillus subtilis (MTCC No. 441), Streptococcus mutans (MTCC No. 497), Escherichia coli (MTCC No. 739) and Pseudomonas aeruginosa (MTCC No. 1934). The results shows that B. subtilis, and E. coli were more sensitive to silver nanoparticles and its size, indicating the superior antimicrobial efficacy of silver nanoparticles. 

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