Substituent effects on absorption and fluorescence spectra of carbostyrils

Radiative and non-radiative (Forster type) energy transfer processes in a dye mixture of FDS and Rh B in methanol under cw Ar ion laser excitation were investigated for fixed donor concentration and varying acceptor concentration. It is found that most of the pump power absorbed by FDS is transferred to Rh B as a useful pump power. Transfer probability ( P DA ), transfer efficiency both radiative ( η R ) and non-radiative ( η NR ) and optical gain ( G ) of the system were studied for various pump powers. The gain characteristics of Rh B are found to alter due to the change in the effective fluorescence lifetime caused by energy transfer reaction. Theoretical calculations were also done to find the total transfer efficiency ( η T ) at various acceptor concentrations to identify the appropriate energy transfer mechanism responsible for gain enhancement in Rh B. Both radiative and non-radiative transfer processes are taken into consideration in all the calculations. Various energy transfer parameters viz. radiative rate constant ( K R ), non-radiative rate constant ( K NR ), critical concentration ( C 0 ), critical radius ( R 0 ) and half quenching concentration ([A] 1/2 ) are calculated by using the Stern–Volmer plots and concentration dependence of radiative and non-radiative transfer efficiencies. Concentration and pump power dependence of the peak gain and lasing wavelengths of the energy transfer dye lasers (ETDL) have also been studied. The experimental results show that the dominant mechanism responsible for the efficient excitation transfer in this mixture is of radiative nature, whereas the long range dipole–dipole (d–d) interaction (Forster type) is comparatively smaller.

Energy transfer and optical gain studies of FDS: Rh B dye mixture investigated under cw laser excitation

The Ba(1-x)CaxZryTi(1-y)O3 (BCZT), a lead-free ceramic material, has attracted the scientific community since 2009 due to its large piezoelectric coefficient and resulting high dielectric permittivity. This perovskite material is a characteristic dielectric material for the pulsed power capacitors industry currently, which in turn leads to devices for effective storage and supply of electric energy. After this remarkable achievement in the area of lead-free piezoelectric ceramics, the researchers are exploring both the bulk as well as thin films of this perovskite material. It is observed that the thin film of this materials have outstandingly high power densities and high energy densities which is suitable for electrochemical supercapacitor applications. From a functional materials point of view this material has also gained attention in multiferroic composite material as the ferroelectric constituent of these composites and has provided extraordinary electric properties. This article presents a review on the relevant scientific advancements that have been made by using the BCZT materials for electric energy storage applications by optimizing its dielectric properties. The article starts with a BCZT introduction and discussion of the need of this material for high energy density capacitors, followed by different synthesis techniques and the effect on dielectric properties of doping different materials in BCZT. The advantages of thin film BCZT material over bulk counterparts are also discussed and its use as one of the constituents of mutiferroic composites is also presented. Finally, it summarizes the future prospects of this material followed by the conclusions.

https://www.mdpi.com/1996-1944/12/21/3641/pdf

Dielectric and Energy Storage Properties of Ba(1-x)CaxZryTi(1-y)O3 (BCZT): A Review.

Amplification of green emission of Ho3+ ions in lead silicate glasses by sensitizing with Bi3+ ions

http://nathan.instras.com/documentDB/paper-393.pdf

Energy transfer mechanism between laser dyes doped in ORMOSILs

The tunability of organic dye lasers has been reviewed by investigating the optical gain characteristics of a coumarin 485-rhodamine B (C 485-Rh B) dye mixture in ethanol subject to N 2 laser excitation. The energy transfer parameters (rate constants of radiative and non-radiative energy transfer processes and the critical transfer radius) have been evaluated with the help of Stern-Volmer plots and the pump power dependence of the gain. The calculated values of radiative and non-radiative energy transfer processes are 0.86 × 10 −11 and 0.45 × 10 −11 L mol −1 s −1 respectively, which shows that the two processes are contributing equally in the present mixture.

Energy transfer excitation in an N2-laser-pumped coumarin 485-rhodamine B dye mixture through optical gain characteristics

Concentration dependent threshold exciting intensity in coumarin 500 and coumarin 485

Glasses with composition xWO 3 .(30-x)Li 2 O.70B 2 O 3 containing 2 mol % V 2 O 5 have been prepared over the range 0≤ x≤ 15 (x is in mol % and in steps of 2.5). The electron paramagnetic resonance (EPR) spectra of VO 2+ in these glasses have been recorded on X-band (ν ≈ 9.14 GHz) at room temperature (RT). The spin Hamiltonian parameters, dipolar hyperfine coupling parameter, P and Fermi contact interaction parameter, K, have been calculated. It has been found that V 4+ ions in these glasses exist as VO 2+ in octahedral coordination with a tetragonal distortion. Results suggest that the tetragonality of the V 4+ O 6 complex changes with change in WO 3 :Li 2 O ratio. Values of theoretical optical basicity have also been calculated.

http://nopr.niscair.res.in/bitstream/123456789/1622/1/IJPAP%2046%286%29%20382-384.pdf

Study of electron paramagnetic resonance in vanadyl doped tungsten lithium borate glasses

Polymer/ZnO nanocomposites have shown a great scientific interest in linear optical properties due to a wide range of applications in the optical devices. The nanocomposites were prepared by mixing the ZnO nanoparticles with Polystyrene (PS) as polymer matrix. Different concentrations of ZnO nanoparticles were used as fillers in the nanocomposites. In the presented work, the PS/ZnO nanocomposite foils have been prepared by using the casting method. The as prepared nanocomposite foils were characterized by using XRD (X-ray diffraction) as well as UV-Visible (UV- Vis) spectroscopy. The transmittance and absorbance of these foils were evaluated from UV-Vis spectra. Transmittance spectra have shown low transmittance in UV region which is inversely related to the concentration of ZnO nanoparticles in these nanocomposite. These nanocomposite foils were found to be highly transparent throughout the visible region and absorb UV light. The observation highlights the possible prospects of these foils in UV shielding applications.

Sujata Sanghi

Papers

Energy transfer excitation in an N2-laser-pumped coumarin 485-rhodamine B dye mixture through optical gain characteristics

Concentration dependent threshold exciting intensity in coumarin 500 and coumarin 485

Study of electron paramagnetic resonance in vanadyl doped tungsten lithium borate glasses

Optical properties of PS/ZnO nanocomposites foils prepared by casting method

Gain measurements in binary and ternary dye mixture solutions under nitrogen laser excitation