Tanu Mimani Rattan

One-Step Synthesis of Colloidal Quantum Dots of Iron Selenide Exhibiting Narrow Range Fluorescence in the Green Region

The instantaneous isolation of green fluorescent colloidal quantum dots of iron selenide capped with biocompatible oleic acid is reported in this study. These iron-containing quantum dots also serve as a safe alternative to the conventionally used metal-chalcogenide systems in which the heavy metal component is usually toxic. The isolated colored colloidal solutions exhibited intense green fluorescence on exposure to ultraviolet light, which was also confirmed by photoluminescence spectroscopy. The isolated product was subjected to dynamic light scattering and transmission electron microscopy, and the particles were found to exhibit spherical morphology with an average diameter of 6–8 nm, confirming the isolation of quantum dots. The isolated iron selenide quantum dots have promising potential towards bioimaging and sensing, due to the biocompatible coating of oleic acid and iron, which also allows possibility of further chemical derivatization.

Nano Calcium-Aluminum Mixed Oxide: A Novel and Effective Material for Defluoridation of Drinking Water

In the present study nano calcium-aluminum mixed oxide material (NCAMO) was synthesized by solution combustion method in 1:1, 1:2, 4:1, 3:2 molar ratios of calcium and aluminum nitrates as oxidizers and urea as fuel for an efficient adsorption of fluoride from drinking water. Molar composition of 1:1 ratio was found to exhibit better adsorption properties and the same was characterized by XRD, FESEM, and FTIR. The optimized conditions for maximum adsorption capacity were achieved at pH4 with contact time of 4 hours by adding 1 g/L of NCAMO to initial fluoride concentration of 8 mg/L. The sorption of fluoride on NCAMO followed Langmuir isotherm model strongly suggested monolayer adsorption. The calculated equilibrium adsorption capacity 23.7 mg/g of NCAMO strongly suggests the dominance of monolayer adsorption process. The adsorption kinetics was well described by pseudo-second order equation confirming chemisorption.

Vanadium pentoxide nanoparticles based saturable absorbers

Vanadium pentoxide (V2O5) nanoparticles were synthesized by solution combustion method. The particle size reduction of the as-synthesized sample was achieved through ball milling. The as-synthesized and the ball milled samples were further characterized using XRD, TEM, EDX, UV-Visible and FTIR spectroscopy. Open-aperture z-scan technique was employed to study the nonlinear optical behavior of the synthesized samples and the commercially available V2O5 (bulk) using a second harmonic (532 nm) of Nd: YAG laser with 15 ns pulse width. We observed that the nonlinear absorption process was dependent on particle size as the synthesized and ball milled nanoparticles exhibited saturable absorption behavior while bulk V2O5 exhibited a transition to reverse saturable absorption behavior at the same incident laser intensity.

Cu2ZnSnS4 synthesized through a low-cost reflux method

Abstract The chalcopyrite semiconductors belonging to the I2-II-IV-VI4 class are emerging as promising absorber materials for photovoltaic applications. Among them, Cu2ZnSnS4 (CZTS) has been gaining importance due to its high absorption coefficient and optimum band-gap. To make CZTS an economically viable alternative, in this study, the CZTS powder has been synthesized via a low-cost, environment-friendly reflux method. In the current method, the salts of the respective metals were taken as initial precursors, and thiourea was used as a precursor for sulfur. The stoichiometric amounts of the precursors were taken in distilled water and the solution was refluxed for 8 h. The products were filtered and washed with distilled water and ethanol consecutively. Phase identification was done using powder X-ray diffraction (given by the reference pattern JCPDS card no. #00-026-0575) and Raman spectroscopy analysis (corresponding Raman shifts for CZTS: 288 and 338 cm-1). The band gap of the compound was calculated from the UV-visible spectroscopy and found to be 1.4 eV.

Surface plasmon coupled emission studies on engineered thin film hybrids of nano α−Al2O3 on silver

We report the first time engineering and fabrication of a novel thin film hybrid of nano α-alumina doped in a polyvinyl alcohol (PVA) matrix along with rhodamine b (Rh.B) on a silver thin film. Silver films of 50 nm thickness on glass slides were fabricated by thermal evaporation. Nano α-alumina was synthesized through the combustion route and characterized by XRD. The α-alumina was dispersed in the PVA-Rh.B matrix by tip sonication. The resultant solution was spin coated on the Ag thin film at 3000 rpm to generate an overcoat of ∼30 nm. We have designed and constructed an opto-mechanical setup for performing the SPCE studies. Excitation with a 532 nm continuous laser, led to the coupling of the energy of Rh.B emission to the surface plasmon modes of silver. The emission @ 580 nm was recorded using an Ocean Optics{copyright, serif} fiber optic spectrometer. Calculation of the ratio of signal intensity between the directional SPCE and isotropic fluorescence gives us the factor of signal enhancements which ...