493-498Hydrocarbon-insoluble derivatives of the type M(deaH)2 (M = Co, Ni, Cu(II); deaH2 = dietha... more 493-498Hydrocarbon-insoluble derivatives of the type M(deaH)2 (M = Co, Ni, Cu(II); deaH2 = diethanolamine) on reactions with Al(OPri)3 in 1:2 molar ratio yield hydrocarbon-soluble, monomeric heterobimetallic derivatives [{Al(OPri)2}2M(dea)2]· A different type of soluble heteroleptic derivatives has been prepared by the reactions of M{Al(OPri)4}2 with deaH2 in 1:1, 1:2 and 1:3 molar ratios. The reaction of M{Al(OPri)4}2 with four equivalents of diethanolamine yields a benzene insoluble product of composition M {Al(dea}2}2. All these new derivatives have been characterized by elemental analyses, molecular weight measurements and spectroscopic (Electronic and IR) studies
Abstract In the present work, the optical properties of transition metal (Mn, Fe, Cu and Ag) dope... more Abstract In the present work, the optical properties of transition metal (Mn, Fe, Cu and Ag) doped ZnS nanoparticles in PVK polymer composites have been studied. The pure and transition metal (TM) doped ZnS nanoparticles were prepared by co-precipitation method and PVK/ZnS(TM) nanocomposites were synthesized by spin coating technique. The nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), optical absorption, energy and time-resolved photoluminescence spectroscopic techniques. The XRD patterns suggest the formation of the cubic phase of ZnS nanoparticles while FTIR spectroscopy reveals the incorporation of transition metal dopants in ZnS nanoparticles. The wide variation in surface morphology for differently doped nanoparticles in PVK based composites has been observed from FESEM technique. The optical gap has been found to increase with nanoparticle incorporation while the increased luminescence quenching is observed for PVK/ZnS:Mn nanocomposites. The time-resolved photoluminescence reveals a change in the lifetime of charge carriers for these composites. These results are important for designing new organic/inorganic nanocomposites for emerging technologies.
In the present work, the organic/inorganic hybrid nanocomposites of polyvinyl carbazole (PVK) wit... more In the present work, the organic/inorganic hybrid nanocomposites of polyvinyl carbazole (PVK) with differently (bare, CdO, ZnS, ZnO) capped CdS nanoparticles were evaluated for their luminescent properties. The bare CdS and CdS/X nanoparticles were synthesized by co-precipitation and PVK–CdS/X nanocomposites were prepared by spin coating technique. The synthesized nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), optical absorption and photoluminescence spectroscopic techniques. The crystallite size was calculated from the XRD data while the TEM patterns confirm the spherical shape of the nanoparticles. The addition of CdS/ZnS nanoparticles gave the highest luminescence while CdS/CdO nanoparticles favor the decreased luminescence of PVK in PVK–CdS/X nanocomposites. The variation in luminescence is also supported by the analysis of fluoresce decay curves. These results are very important in selecting the shell material in core/shell nanoparticles to be incorporated in the development of new and efficient materials.
This work presents a systematic study of the effect of ZnSe nanocrystals (NCs) concentration on t... more This work presents a systematic study of the effect of ZnSe nanocrystals (NCs) concentration on the optical and luminescent properties of poly N-vinylcarbazole (PVK) polymer nanocomposites. The ZnSe nanocrystals were synthesized by a simple coprecipitation chemical route, while PVK:ZnSe nanocomposite films were fabricated using the spin coating technique. The samples were characterized by XRD, TEM, SEM, UV-Vis and fluorescence techniques. The X-ray diffraction and TEM studies confirmed the particle size, microstructure and spherical shape of the synthesized nanocrystals. The ZnSe nanocrystals in PVK caused a decrease in optical gap with increasing concentration of nanocrystals. The emission spectra exhibited augmentation in intensity up to 70 wt.% of nanoparticles while further addition resulted in a decrease in luminescence. The structure-property relationships obtained for the present system are important for developing low cost illumination devices.
Organic/inorganic hybrid materials consisting of quantum dots and conjugate polymers are importan... more Organic/inorganic hybrid materials consisting of quantum dots and conjugate polymers are important for the application in light emitting devices. In the present work, we have studied the effect of CdS and CdS/ZnO nanoparticle addition on the structure and fluorescence properties of spin coated PVK (poly(N-vinyl carbozole)) nanocomposite films. CdS nanoparticles were synthesized by simple co-precipitation technique and ZnO shell was grown on the CdS nanoparticles by simple wet chemical approach. The nanoparticles and the hybrid nanocomposites have been characterized by using XRD, SEM, FT-IR, optical absorption and fluorescence spectroscopic techniques. The absorption peak for pure PVK remains at 345.5 nm accompanied with minor hump ~480 nm resulting from the incorporation of nanoparticles. It has been observed that the addition of nanoparticles to the hybrid material results in the enhancement of fluorescence intensity at 410 nm to 450 nm spectral regions. These results are important...
Synthesis of nanoparticles of cadmium selenide (CdSe) was carried out using sonochemical method w... more Synthesis of nanoparticles of cadmium selenide (CdSe) was carried out using sonochemical method with cadmium acetate and sodium selenite as precursors. Hydrazine hydrate and ammonia were used to control the size of the nanoparticles. The crystalline nature and particle size of the samples were characterized by powder X-Ray Diffraction analysis. The FTIR results show that the frequency of absorption at 890 cm -1 decreases as the concentration of dopant increases. The absorption exhibit blue- shift with decreasing nanoparticle size, which is attributed to quantum confinement effect. The refractive index and dielectric constant is dependent on absorbance. The extinction coefficient values increases with particle size.
Bacillus sp. PS-7, isolated from the hot springs of Manikaran (HP), India, produced very high lev... more Bacillus sp. PS-7, isolated from the hot springs of Manikaran (HP), India, produced very high levels of thermostable α-amylase by solid state fermentation (SSF) in Erlenmeyer flasks and enamel coated metallic trays. Productivity was affected by the nature of the solid ...
493-498Hydrocarbon-insoluble derivatives of the type M(deaH)2 (M = Co, Ni, Cu(II); deaH2 = dietha... more 493-498Hydrocarbon-insoluble derivatives of the type M(deaH)2 (M = Co, Ni, Cu(II); deaH2 = diethanolamine) on reactions with Al(OPri)3 in 1:2 molar ratio yield hydrocarbon-soluble, monomeric heterobimetallic derivatives [{Al(OPri)2}2M(dea)2]· A different type of soluble heteroleptic derivatives has been prepared by the reactions of M{Al(OPri)4}2 with deaH2 in 1:1, 1:2 and 1:3 molar ratios. The reaction of M{Al(OPri)4}2 with four equivalents of diethanolamine yields a benzene insoluble product of composition M {Al(dea}2}2. All these new derivatives have been characterized by elemental analyses, molecular weight measurements and spectroscopic (Electronic and IR) studies
Abstract In the present work, the optical properties of transition metal (Mn, Fe, Cu and Ag) dope... more Abstract In the present work, the optical properties of transition metal (Mn, Fe, Cu and Ag) doped ZnS nanoparticles in PVK polymer composites have been studied. The pure and transition metal (TM) doped ZnS nanoparticles were prepared by co-precipitation method and PVK/ZnS(TM) nanocomposites were synthesized by spin coating technique. The nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), optical absorption, energy and time-resolved photoluminescence spectroscopic techniques. The XRD patterns suggest the formation of the cubic phase of ZnS nanoparticles while FTIR spectroscopy reveals the incorporation of transition metal dopants in ZnS nanoparticles. The wide variation in surface morphology for differently doped nanoparticles in PVK based composites has been observed from FESEM technique. The optical gap has been found to increase with nanoparticle incorporation while the increased luminescence quenching is observed for PVK/ZnS:Mn nanocomposites. The time-resolved photoluminescence reveals a change in the lifetime of charge carriers for these composites. These results are important for designing new organic/inorganic nanocomposites for emerging technologies.
In the present work, the organic/inorganic hybrid nanocomposites of polyvinyl carbazole (PVK) wit... more In the present work, the organic/inorganic hybrid nanocomposites of polyvinyl carbazole (PVK) with differently (bare, CdO, ZnS, ZnO) capped CdS nanoparticles were evaluated for their luminescent properties. The bare CdS and CdS/X nanoparticles were synthesized by co-precipitation and PVK–CdS/X nanocomposites were prepared by spin coating technique. The synthesized nanocomposites were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), optical absorption and photoluminescence spectroscopic techniques. The crystallite size was calculated from the XRD data while the TEM patterns confirm the spherical shape of the nanoparticles. The addition of CdS/ZnS nanoparticles gave the highest luminescence while CdS/CdO nanoparticles favor the decreased luminescence of PVK in PVK–CdS/X nanocomposites. The variation in luminescence is also supported by the analysis of fluoresce decay curves. These results are very important in selecting the shell material in core/shell nanoparticles to be incorporated in the development of new and efficient materials.
This work presents a systematic study of the effect of ZnSe nanocrystals (NCs) concentration on t... more This work presents a systematic study of the effect of ZnSe nanocrystals (NCs) concentration on the optical and luminescent properties of poly N-vinylcarbazole (PVK) polymer nanocomposites. The ZnSe nanocrystals were synthesized by a simple coprecipitation chemical route, while PVK:ZnSe nanocomposite films were fabricated using the spin coating technique. The samples were characterized by XRD, TEM, SEM, UV-Vis and fluorescence techniques. The X-ray diffraction and TEM studies confirmed the particle size, microstructure and spherical shape of the synthesized nanocrystals. The ZnSe nanocrystals in PVK caused a decrease in optical gap with increasing concentration of nanocrystals. The emission spectra exhibited augmentation in intensity up to 70 wt.% of nanoparticles while further addition resulted in a decrease in luminescence. The structure-property relationships obtained for the present system are important for developing low cost illumination devices.
Organic/inorganic hybrid materials consisting of quantum dots and conjugate polymers are importan... more Organic/inorganic hybrid materials consisting of quantum dots and conjugate polymers are important for the application in light emitting devices. In the present work, we have studied the effect of CdS and CdS/ZnO nanoparticle addition on the structure and fluorescence properties of spin coated PVK (poly(N-vinyl carbozole)) nanocomposite films. CdS nanoparticles were synthesized by simple co-precipitation technique and ZnO shell was grown on the CdS nanoparticles by simple wet chemical approach. The nanoparticles and the hybrid nanocomposites have been characterized by using XRD, SEM, FT-IR, optical absorption and fluorescence spectroscopic techniques. The absorption peak for pure PVK remains at 345.5 nm accompanied with minor hump ~480 nm resulting from the incorporation of nanoparticles. It has been observed that the addition of nanoparticles to the hybrid material results in the enhancement of fluorescence intensity at 410 nm to 450 nm spectral regions. These results are important...
Synthesis of nanoparticles of cadmium selenide (CdSe) was carried out using sonochemical method w... more Synthesis of nanoparticles of cadmium selenide (CdSe) was carried out using sonochemical method with cadmium acetate and sodium selenite as precursors. Hydrazine hydrate and ammonia were used to control the size of the nanoparticles. The crystalline nature and particle size of the samples were characterized by powder X-Ray Diffraction analysis. The FTIR results show that the frequency of absorption at 890 cm -1 decreases as the concentration of dopant increases. The absorption exhibit blue- shift with decreasing nanoparticle size, which is attributed to quantum confinement effect. The refractive index and dielectric constant is dependent on absorbance. The extinction coefficient values increases with particle size.
Bacillus sp. PS-7, isolated from the hot springs of Manikaran (HP), India, produced very high lev... more Bacillus sp. PS-7, isolated from the hot springs of Manikaran (HP), India, produced very high levels of thermostable α-amylase by solid state fermentation (SSF) in Erlenmeyer flasks and enamel coated metallic trays. Productivity was affected by the nature of the solid ...
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Papers by Kanupriya Sharma