PD Sahare | University of Delhi (original) (raw)

Papers by PD Sahare

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2003

physica status solidi (a), 2007

Journal of Physics D: Applied Physics, 2007

K3Na(SO4)2 : Eu nanocrystalline powder was synthesized by the chemical co-precipitation method. T... more K3Na(SO4)2 : Eu nanocrystalline powder was synthesized by the chemical co-precipitation method. The x-ray diffraction pattern of the nanomaterials shows a hexagonal structure for its crystals having grain size of ∼28 nm. Transmission electron microscopy revealed that the K3Na(SO4)2 : Eu nanoparticles are single crystals with almost a uniform shape and size. Thermoluminescence (TL) was taken after irradiating the samples

Radiation Measurements, 2006

Nanocrystalline CaSO 4 : Dy of grain size 30 nm has been prepared by the chemical co-precipitatio... more Nanocrystalline CaSO 4 : Dy of grain size 30 nm has been prepared by the chemical co-precipitation method and its photoluminescence (PL) and thermoluminescence (TL) characteristics have been studied. The PL emission spectrum of the nanophosphor resembles with that of the ...

Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation method. The... more Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation method. The
impurity concentration was varied in the range of 0.5e4.0 mol%. The structure of the synthesized material
was confirmed using powder XRD analysis. TEM images of the nanoparticles show their size
occurring mostly in the range of 35e40 nm, with clusters of some impurity phases formed on annealing
of the material at higher temperatures. Detailed studies on TL showed that the structures of glow curves
depend on Mn concentrations and annealing temperatures. Optimization of the concentration and
annealing temperature showed that the sample (doped with 3.0 mol% and annealed at 673 K) has almost
a single dosimetric glow peak appearing at around 492 K. EPR and PL spectra were further studied to
understand the reasons for changes in the glow curve structures. All detailed studies on TL, PL and EPR
showed that the changes in glow curve structures are caused not only by the stress connected with the
difference in ionic radii of host Ca2þ and the guest impurity Mn3þ/Mn2þ, but are also governed by other
reasons, like diffusion of atmospheric oxygen and formation of impurity aggregates, such as, MnO2,
Mn3O4, etc. This is true not only for nanocrystalline CaF2:Mn but could also be so for the bulk CaF2:Mn
(TLD-400) and would thus help in understanding complex glow curve structure, high fading and the loss
of reusability on annealing beyond 673 K.

Journal of Physics D: Applied Physics, 2007

Fluorescence sensitization of a 2,2'-([1,1'-biphenyl]-4,4'-diyldi-2,1-ethenediyl)-... more Fluorescence sensitization of a 2,2'-([1,1'-biphenyl]-4,4'-diyldi-2,1-ethenediyl)-bis-benzenesulfonic acid disodium salt (Stilbene 3) solution in ethanol (EtOH) due to the presence in aqueous solution of ammonia is reported here. In this study sensitization of the dye solution due to the presence of ammonia was observed. It was also found that the observed sensitization is dynamic in nature. Sensitization of the fluorescence of the indicator also has full reversibility. An optical sensor for the detection of ammonia could thus be constructed using these properties of the dye and the sensitizer.

Spectroscopy Letters, 2013

ABSTRACT In the present study, Zn1−xNixS (x = 0.0–0.8 mol%) nanoparticles were prepared through t... more ABSTRACT In the present study, Zn1−xNixS (x = 0.0–0.8 mol%) nanoparticles were prepared through the chemical route and the synthesis involved the mixing and drying of zinc acetate and sodium sulphide in an appropriate ratio with the addition of Ni2+ at a proper concentration. The structural and spectroscopic studies are investigated by X-ray diffraction (XRD), absorption spectra, emission and excitation spectra, and Raman spectra. Compared with that of the pristine materials, the absorption band-edge demonstrates an apparently blue shift, which is attributed to the quantum size effect. The average particle size of ZnS nanoparticles is in the range of 2–4 nm deduced from the XRD line broadening. Excited at about 330 nm, a blue emission band at 425 nm can be observed, which corresponds to Ni2+ luminescent center; this result is consistent with the postulation that Ni2+ replaced the Zn2+ ions in the lattice of ZnS nanocrystals. Excitation spectra also confirm the above postulation. The effect of different concentrations of nickel is also studied by Raman spectra.

Advanced Porous Materials, 2013

Sensor Letters, 2013

ABSTRACT Fluorescein sodium had been incorporated into the Mesoporous nano silica MCM-41. Synthes... more ABSTRACT Fluorescein sodium had been incorporated into the Mesoporous nano silica MCM-41. Synthesized MCM-41 material was characterized using SEM, TEM. An optical study has been carried out using photoluminescence spectrophotometer. Photoluminescence spectra of different concentration of fluorescein sodium incorporated in MCM-41 had been studied to determine maximum quantum yield. High quantum yield was obtained at 10–3 M concentration. Thus, fluorescein sodium incorporated in MCM-41 pellets of 10–3M concentration had been used as a sensor material for sensing the sulphur dioxide gas. Fluorescein sodium incorporated in MCM-41 pellets incorporated into a fluorescence spectroscopic instrument for the online detection of sulphur dioxide gas. The fluorescence response of the MCM-41/fluorescein sodium sulphur dioxide sensing material was very sensitive at the photoluminescence excitation wavelength of 480 nm. A high linear correlation was achieved for 80 ppm levels of sulphur dioxide gas. The response time for the quantitative detection of sulphur dioxide gas concentrations ranging from 10 to 80 ppm was only a few minutes. The lower detection limit achieved was 10 ppm. These features together make this mesoporous nano silica material very promising for optical sensing applications.

Journal of Materials Science & Technology, 2013

ABSTRACT Spherically shaped mesoporous silica nanoparticles (MSNs) having honeycomb like porous s... more ABSTRACT Spherically shaped mesoporous silica nanoparticles (MSNs) having honeycomb like porous structure were synthesized by sol-gel method. Transmission electron microscopy (TEM), surface area measurement and X-ray diffractometry were used, revealing the hexagonal shaped pores in MSNs. MSNs with surface area of 1104.47 m(2)/g and large porosity of 2.8 nm in pore diameter and 0.87 cm(3)/g in pore volume were synthesized. TEM images showed spherical nanoparticles of similar to 200-300 nm having honeycomb like pores. Stilbene 420 laser dye was incorporated in MSNs and photoluminescence spectra of stilbene 420 in MSNs and in ethanol had been studied. Stilbene 420 laser dye showed high fluorescence intensity in the fluorescence spectra of MSNs than that of ethanol. The prolonged fluorescence lifetime decay of stilbene in MSNs and the increase in fluorescence intensity for stilbene 420 in MSNs would make these nanomaterials more useful for nanosensors and nanolasers application.

Journal of Materials Science Letters, 1992

Carbon, 2011

We report the production of high quality single and double layer graphene from sonication and cen... more We report the production of high quality single and double layer graphene from sonication and centrifugation of re-exfoliated expanded graphite (EG) in an organic solvent. The prepared graphene-sheets are identified by Ultraviolet–visible spectroscopy and characterized using different techniques. Transmission and scanning electron microscopy observations show that the graphene-sheets have an area of ∼(12×10)μm2. The selected area electron diffraction analysis and

Radiation Measurements, 2007

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2003

physica status solidi (a), 2003

Journal of Physics D: Applied Physics, 2004

ABSTRACT Decreasing the particle size results in a decrease in pyroelectroluminescence (PEL) in L... more ABSTRACT Decreasing the particle size results in a decrease in pyroelectroluminescence (PEL) in LiNaSO4 : Eu. The nanocrystalline LiNaSO4 : Eu gives no PEL, making it much more suitable for thermoluminescence dosimetry of low doses of ionizing radiations such as x-rays and gamma rays, compared with the microcrystalline LiNaSO4 : Eu.

Journal of Physics D: Applied Physics, 1990

ABSTRACT

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2003

physica status solidi (a), 2007

Journal of Physics D: Applied Physics, 2007

K3Na(SO4)2 : Eu nanocrystalline powder was synthesized by the chemical co-precipitation method. T... more K3Na(SO4)2 : Eu nanocrystalline powder was synthesized by the chemical co-precipitation method. The x-ray diffraction pattern of the nanomaterials shows a hexagonal structure for its crystals having grain size of ∼28 nm. Transmission electron microscopy revealed that the K3Na(SO4)2 : Eu nanoparticles are single crystals with almost a uniform shape and size. Thermoluminescence (TL) was taken after irradiating the samples

Radiation Measurements, 2006

Nanocrystalline CaSO 4 : Dy of grain size 30 nm has been prepared by the chemical co-precipitatio... more Nanocrystalline CaSO 4 : Dy of grain size 30 nm has been prepared by the chemical co-precipitation method and its photoluminescence (PL) and thermoluminescence (TL) characteristics have been studied. The PL emission spectrum of the nanophosphor resembles with that of the ...

Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation method. The... more Nanocrystalline samples of Mn-doped CaF2 were synthesized by chemical coprecipitation method. The
impurity concentration was varied in the range of 0.5e4.0 mol%. The structure of the synthesized material
was confirmed using powder XRD analysis. TEM images of the nanoparticles show their size
occurring mostly in the range of 35e40 nm, with clusters of some impurity phases formed on annealing
of the material at higher temperatures. Detailed studies on TL showed that the structures of glow curves
depend on Mn concentrations and annealing temperatures. Optimization of the concentration and
annealing temperature showed that the sample (doped with 3.0 mol% and annealed at 673 K) has almost
a single dosimetric glow peak appearing at around 492 K. EPR and PL spectra were further studied to
understand the reasons for changes in the glow curve structures. All detailed studies on TL, PL and EPR
showed that the changes in glow curve structures are caused not only by the stress connected with the
difference in ionic radii of host Ca2þ and the guest impurity Mn3þ/Mn2þ, but are also governed by other
reasons, like diffusion of atmospheric oxygen and formation of impurity aggregates, such as, MnO2,
Mn3O4, etc. This is true not only for nanocrystalline CaF2:Mn but could also be so for the bulk CaF2:Mn
(TLD-400) and would thus help in understanding complex glow curve structure, high fading and the loss
of reusability on annealing beyond 673 K.

Journal of Physics D: Applied Physics, 2007

Fluorescence sensitization of a 2,2'-([1,1'-biphenyl]-4,4'-diyldi-2,1-ethenediyl)-... more Fluorescence sensitization of a 2,2'-([1,1'-biphenyl]-4,4'-diyldi-2,1-ethenediyl)-bis-benzenesulfonic acid disodium salt (Stilbene 3) solution in ethanol (EtOH) due to the presence in aqueous solution of ammonia is reported here. In this study sensitization of the dye solution due to the presence of ammonia was observed. It was also found that the observed sensitization is dynamic in nature. Sensitization of the fluorescence of the indicator also has full reversibility. An optical sensor for the detection of ammonia could thus be constructed using these properties of the dye and the sensitizer.

Spectroscopy Letters, 2013

ABSTRACT In the present study, Zn1−xNixS (x = 0.0–0.8 mol%) nanoparticles were prepared through t... more ABSTRACT In the present study, Zn1−xNixS (x = 0.0–0.8 mol%) nanoparticles were prepared through the chemical route and the synthesis involved the mixing and drying of zinc acetate and sodium sulphide in an appropriate ratio with the addition of Ni2+ at a proper concentration. The structural and spectroscopic studies are investigated by X-ray diffraction (XRD), absorption spectra, emission and excitation spectra, and Raman spectra. Compared with that of the pristine materials, the absorption band-edge demonstrates an apparently blue shift, which is attributed to the quantum size effect. The average particle size of ZnS nanoparticles is in the range of 2–4 nm deduced from the XRD line broadening. Excited at about 330 nm, a blue emission band at 425 nm can be observed, which corresponds to Ni2+ luminescent center; this result is consistent with the postulation that Ni2+ replaced the Zn2+ ions in the lattice of ZnS nanocrystals. Excitation spectra also confirm the above postulation. The effect of different concentrations of nickel is also studied by Raman spectra.

Advanced Porous Materials, 2013

Sensor Letters, 2013

ABSTRACT Fluorescein sodium had been incorporated into the Mesoporous nano silica MCM-41. Synthes... more ABSTRACT Fluorescein sodium had been incorporated into the Mesoporous nano silica MCM-41. Synthesized MCM-41 material was characterized using SEM, TEM. An optical study has been carried out using photoluminescence spectrophotometer. Photoluminescence spectra of different concentration of fluorescein sodium incorporated in MCM-41 had been studied to determine maximum quantum yield. High quantum yield was obtained at 10–3 M concentration. Thus, fluorescein sodium incorporated in MCM-41 pellets of 10–3M concentration had been used as a sensor material for sensing the sulphur dioxide gas. Fluorescein sodium incorporated in MCM-41 pellets incorporated into a fluorescence spectroscopic instrument for the online detection of sulphur dioxide gas. The fluorescence response of the MCM-41/fluorescein sodium sulphur dioxide sensing material was very sensitive at the photoluminescence excitation wavelength of 480 nm. A high linear correlation was achieved for 80 ppm levels of sulphur dioxide gas. The response time for the quantitative detection of sulphur dioxide gas concentrations ranging from 10 to 80 ppm was only a few minutes. The lower detection limit achieved was 10 ppm. These features together make this mesoporous nano silica material very promising for optical sensing applications.

Journal of Materials Science & Technology, 2013

ABSTRACT Spherically shaped mesoporous silica nanoparticles (MSNs) having honeycomb like porous s... more ABSTRACT Spherically shaped mesoporous silica nanoparticles (MSNs) having honeycomb like porous structure were synthesized by sol-gel method. Transmission electron microscopy (TEM), surface area measurement and X-ray diffractometry were used, revealing the hexagonal shaped pores in MSNs. MSNs with surface area of 1104.47 m(2)/g and large porosity of 2.8 nm in pore diameter and 0.87 cm(3)/g in pore volume were synthesized. TEM images showed spherical nanoparticles of similar to 200-300 nm having honeycomb like pores. Stilbene 420 laser dye was incorporated in MSNs and photoluminescence spectra of stilbene 420 in MSNs and in ethanol had been studied. Stilbene 420 laser dye showed high fluorescence intensity in the fluorescence spectra of MSNs than that of ethanol. The prolonged fluorescence lifetime decay of stilbene in MSNs and the increase in fluorescence intensity for stilbene 420 in MSNs would make these nanomaterials more useful for nanosensors and nanolasers application.

Journal of Materials Science Letters, 1992

Carbon, 2011

We report the production of high quality single and double layer graphene from sonication and cen... more We report the production of high quality single and double layer graphene from sonication and centrifugation of re-exfoliated expanded graphite (EG) in an organic solvent. The prepared graphene-sheets are identified by Ultraviolet–visible spectroscopy and characterized using different techniques. Transmission and scanning electron microscopy observations show that the graphene-sheets have an area of ∼(12×10)μm2. The selected area electron diffraction analysis and

Radiation Measurements, 2007

Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2003

physica status solidi (a), 2003

Journal of Physics D: Applied Physics, 2004

ABSTRACT Decreasing the particle size results in a decrease in pyroelectroluminescence (PEL) in L... more ABSTRACT Decreasing the particle size results in a decrease in pyroelectroluminescence (PEL) in LiNaSO4 : Eu. The nanocrystalline LiNaSO4 : Eu gives no PEL, making it much more suitable for thermoluminescence dosimetry of low doses of ionizing radiations such as x-rays and gamma rays, compared with the microcrystalline LiNaSO4 : Eu.

Journal of Physics D: Applied Physics, 1990

ABSTRACT