Madhusudan Bhide - Academia.edu (original) (raw)

Papers by Madhusudan Bhide

Electron Paramagnetic Resonance (EPR) technique is useful to quantify the paramagnetic species in... more Electron Paramagnetic Resonance (EPR) technique is useful to quantify the paramagnetic species in any matrix. The unpaired electrons present in paramagnetic materials have non – zero spin value, have an associated spin magnetic moment. When such a system is subjected to an external magnetic field, electronic Zeeman splitting of ground level state occurs. On application of suitable stimulant microwave energy, the electrons flip between the Zeeman levels of ground state, result in resonant absorption of the microwave energy. The intensity of resonant absorption signal is proportional to the concentration of the unpaired electrons in the irradiated material, could lead to possible use of such materials in EPR dosimetric applications. New materials were investigated for EPR dosimetry, wherein the radiation induced paramagnetic species retains the radiation signatures, lead to idea on radiation dose. Few of the materials have been identified as prospective EPR dosimeters. The radiation i...

A brief account of the luminescence studies of gemstones ruby,chryso beryl and diamond are given ... more A brief account of the luminescence studies of gemstones ruby,chryso beryl and diamond are given The luminescence of ruby primarily arises due to trivalent chromium impurity, where as the nitrogen-vacancy complexex are the main centres of luminescence in diamond. In the case of diamond surface fluorescence mapping under deep UV excitation is invaluable in detecting the lab grown diamonds.

Superconductor …, 2001

... ofHc1 were obtained at different temperatures and the value of Hc1(0) is found to be 250 G. T... more ... ofHc1 were obtained at different temperatures and the value of Hc1(0) is found to be 250 G. The absorbed microwave power showed ... The authors wish to thank Dr SB Manohar, Head of the Radiochemistry Division, for his keen interest during the course of these investigations. ...

Nuclear Technology, 1989

Uranium-aluminum alloys with a significant enrichment of uranium with 233 U or 23SU serve as nucl... more Uranium-aluminum alloys with a significant enrichment of uranium with 233 U or 23SU serve as nuclear fuels in research reactors. The quality assurance of this fuel requires, among other things, precise knowledge that all trace metal constituents that affect neutron economy, fuel integrity, and fuel fabrication process parameters are well within the specification limits. Trace metal characterization of m U-Al alloy has been carried out by atomic spectrometry. The trace metal constituents of interest are grouped into common metals (

Bulletin of Materials Science, 2014

U 6+ doped BaSO 4 samples were synthesized by precipitation route. PL, TL and EPR investigations ... more U 6+ doped BaSO 4 samples were synthesized by precipitation route. PL, TL and EPR investigations of γ and self α irradiated samples were carried out. PL spectra of these samples give structured broad band peaking around 518 nm with five vibronic bands centred around 498•4, 516•0, 533•7, 554•0 and 575•1 nm, respectively and the average frequency of symmetric stretching of O=U=O in the ground electronic state was found to be 674 cm −1. Trap level spectroscopic studies of U doped BaSO 4 give glow peaks at 411, 488 and 512 K, respectively and their spectral characteristics are typical of UO 2+ 2 emission. EPR studies of γ-irradiated U 6+ :BaSO 4 sample have shown the presence of sulphoxy centred radicals like SO − 4 and SO − 3 in addition to OH • , O − 3 and SH 2−. TSL peaks at 411 and 488 K were correlated with thermal destruction of SO − 4 and SO − 3 radicals.

Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties, 2001

With a view to investigating the nature of weak links in granular superconductors at very dilute ... more With a view to investigating the nature of weak links in granular superconductors at very dilute level, we have studied the low-field microwave absorption signal (below about 50 G) in the electron paramagnetic resonance mode of detection in samples of Tl2BaCa2Cu2O8+δ and YBa2CuO7-δ at different dilution levels in the AlO3 matrix. The signal has been monitored as a function of

Indian Journal of Physics, 2009

Ultrafine M 5 (PO 4) 3 F:Dy 3+ (M = Ca, Ba) phosphors were prepared via combustion process using ... more Ultrafine M 5 (PO 4) 3 F:Dy 3+ (M = Ca, Ba) phosphors were prepared via combustion process using metal nitrates as precursors. The formation of crystalline phosphate was confirmed by X-ray diffraction pattern. The PL excitation spectra show the excitation peaks observed at 250 to 400 nm due to f → f transition of Dy 3+ ion, which are useful for solid-state lighting purpose (mercury free excitation). The PL emission of Dy 3+ ion by 348 nm excitation gave an emission at 489 nm (blue), 582 nm (yellow) and 675 nm (red). All the characteristics of BYR emissions like BGR indicate that Dy doped Ca 5 (PO 4) 3 F and Ba 5 (PO 4) 3 F phosphors are good candidates that can be applied in solid-state lighting phosphor (mercury free excited lamp phosphor) and white light LED.

Journal of Physics D: Applied Physics, 2007

Thermoluminescence (TL), electron spin resonance (ESR) and x ray diffraction studies of CaSO4 : D... more Thermoluminescence (TL), electron spin resonance (ESR) and x ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature treatment were carried out. Analysis of the TL glow curve indicated that the dosimetric glow peak at 240 °C reduces, whereas the low temperature satellite peak increases with the increase in the annealing temperature in the range 650-1000

Journal of Experimental Nanoscience, 2013

White light emitting Sr 2 SiO 4 :Eu 2þ nanoparticles were prepared using reverse micellar route u... more White light emitting Sr 2 SiO 4 :Eu 2þ nanoparticles were prepared using reverse micellar route using Tergitol as a surfactant. The systems were characterised by X-ray diffraction, scanning electron microscopy (SEM), photoluminescence, thermoluminescence (TL), and electron paramagnetic resonance (EPR) spectroscopy. SEM shows the formation of silicate nanorods. Two emission bands of bluish-green at 490 nm (S(I)) and of orange-red at 605 nm (S(II)) were observed. The two emission bands are assigned to the 4f-5d transition of Eu 2þ ions in two different cation sites in a 0-Sr 2 SiO 4 orthorhombic lattices. Gammairradiated Sr 2 SiO 4 :Eu showed the presence of three TL glow peaks at 437, 487 K and weak peak at 540 K; however, no glow was observed in the undoped sample. Reduction of Eu 3þ to Eu 2þ is confirmed by EPR spectroscopy.

Applied Radiation and Isotopes, 2011

CaSO 4 :Dy, CaSO 4 :(Dy, Bi) and CaSO 4 :Bi phosphors were prepared through re-crystallization me... more CaSO 4 :Dy, CaSO 4 :(Dy, Bi) and CaSO 4 :Bi phosphors were prepared through re-crystallization method. Thermoluminescence (TL) characteristics of these phosphor samples were investigated. The radiation induced radical ions formed in these phosphors were investigated using electron paramagnetic resonance (EPR) spectroscopy. The main signals observed in both CaSO 4 :(Dy, Bi) and CaSO 4 :Bi were identified as SO À 4 (II), SO À 4 (?) and SO À 3 (isotropic) with ''g'' values 2.023, 2.0089 and 2.004, respectively. In order to understand the TL mechanism, CaSO 4 :(Dy, Bi) phosphor samples were annealed between 100 and 250 1C and their EPR spectra were studied. It was observed that EPR signal intensities reduce drastically in 250 1C annealed phosphor confirming the role of SO À 4 and SO À 3 types of defect centers in the dosimetric peak. The reduction in the TL sensitivity with increase in Bi 3 + co-dopant in the phosphor samples was correlated with quenching of TL by Bi 3 + ions rather than the reduction in the concentration of the above defect centers. An effort was also made to use the Bi 3 + co-doped CaSO 4 :Dy phosphor for dosimetry of chilled or frozen food irradiation.

Materials Letters, 2005

Systematic magnetic field dependent microwave absorption measurements have been performed on nano... more Systematic magnetic field dependent microwave absorption measurements have been performed on nanocrystalline La 0.6 Pb 0.4 MnO 3 (LPMO) thin films over a temperature range of 77–300 K. In addition to a regular ferromagnetic resonance (FMR) signal below the Curie ...

Nuclear technology

Uranium-aluminum alloys with a significant enrichment of uranium with ²³³U or ²³⁵U serve a... more Uranium-aluminum alloys with a significant enrichment of uranium with ²³³U or ²³⁵U serve as nuclear fuels in research reactors. The quality assurance of this fuel requires, among other things, precise knowledge that all trace metal constituents that affect neutron economy, fuel integrity, and fuel fabrication process parameters are well within the specification limits. Trace metal characterization of ²³⁵U-Al alloy has

Journal of the American Ceramic Society, 2014

ABSTRACT ThO2:Eu3+ nanoparticles were synthesized at 300°C by combustion route using urea as a fu... more ABSTRACT ThO2:Eu3+ nanoparticles were synthesized at 300°C by combustion route using urea as a fuel and characterized by thermogravimetric/differential thermal analysis, X-ray diffraction, transmission electron microscopy, and photoluminescence techniques. To investigate the effect of annealing temperature, as synthesized powder were heated further at 500°C, 700°C, and 900°C. It was observed that extent of asymmetry around Eu3+ at 700°C/900°C is very high as compared to as-prepared or 500°C annealed sample. Based on the time resolved emission spectroscopic investigations, it was inferred that two different types of Eu3+ ions were present in the ThO2 nanoparticles. In ThO2 structure, Eu3+ ions occupy two sites; cubic (Oh) and noncubic (<C2v) as can be confirmed from our emission studies. Short-lived species T1 (~1.3–3.4 ms) predominates at higher annealing temperature arises because of Eu3+ ions occupying noncubic (<C2v) sites without inversion symmetry, whereas long-lived species T2 (~4.6–6.6 ms) can be ascribed to Eu3+ ions occupying cubic sites (Oh) with inversion symmetry.

Indian Journal of Physics, 2009

Radiation Physics and Chemistry, 2010

Electron paramagnetic resonance (EPR) investigations of Li 2 C 2 O 4 , Na 2 C 2 O 4 mixed in prop... more Electron paramagnetic resonance (EPR) investigations of Li 2 C 2 O 4 , Na 2 C 2 O 4 mixed in proportion 1:0, 0:1, 1:1, 2:1 and 3:1 were carried out to measure the absorbed dose from photons and thermal neutrons in a mixed radiation field. A single line spectrum of CO 2 À radical anion centered around g ¼ 2.00457 0.0005 was obtained in the respective cases on gamma and neutron irradiation. Except Na 2 C 2 O 4 , other mixtures had shown increase in line width on neutron irradiation possibly due to relaxation effects. Of all combinations, the 2:1 mixture is the more sensitive material for gamma and thermal neutrons. Intensity of CO 2 À radical signal in 2:1 Li 2 C 2 O 4 :Na 2 C 2 O 4 mixture was found to be linear from 0.006 to 11 kGy for gamma and 40-1530 kGy for thermal neutron doses. Radical signal was found to be stable over a period of 300 days with marginal fading of less than 1 percent. Experimental results thus obtained suggest 2:1 Li 2 C 2 O 4 :Na 2 C 2 O 4 mixture as the potential neutron dosimeter for medium and high dose range.

Philosophical Magazine Part B, 1999

We report the synthesis, magnetic characteristics and electron paramagnetic resonance (EPR) data ... more We report the synthesis, magnetic characteristics and electron paramagnetic resonance (EPR) data on the new hexacyanometallate-based bimetallic molecular compound [Ni(pn)2]3 [FeCN6]2 12H2O, where pn 1,2-propanediamine, which shows bulk ferromagnetic order below 19K. It is a soft magnet exhibiting a rather weak hysteresis. The EPR spectra show a fine structure, characteristic of an S 3/2 state, in a very narrow temperature

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008

Eu-activated Y2O3 phosphors were prepared by combustion synthesis and also by precipitation techn... more Eu-activated Y2O3 phosphors were prepared by combustion synthesis and also by precipitation techniques. Photoluminescence and X-ray excited luminescence of prepared Y2O3:Eu phosphor, under two different techniques were compared and reported in this paper. Y2O3:Eu3+ phosphor were prepared by precipitation technique followed by annealing at 900°C. It gives cubic nature of the particle that may be more favourable for high lumen

Research on Chemical Intermediates, 2003

Absorption spectrophotometric studies indicated that in chloroform¯-carotene reacted with NO 2 wi... more Absorption spectrophotometric studies indicated that in chloroform¯-carotene reacted with NO 2 with a stoichiometry of 1 : 2. To understand the reaction mechanism, free radical intermediates produced during their reaction were trapped by spin traps 2-methyl-2-nitroso propane (MNP) and 4-pyridyl-1-oxide-N-1-but yl nitrone (POBN). The resulting stable spin adducts were detected by electron spin resonance (ESR) spectroscopy. NO 2 alone did not interact with spin traps, but introduction of¯-carotene-generatedESR signals with different nitrogen and hydrogen hyper ne coupling constants (A N and A H) characteristic of the trapped radical. Two possible pathways exist for the reaction of NO 2 with¯-carotene, viz., electron transfer and addition to the polyene chain. Our ESR results supported an addition mechanism, where formation of carbon-centered [NO 2 ¢ ¢ ¢¯-carotene] free radical adduct was observed.

Electron Paramagnetic Resonance (EPR) technique is useful to quantify the paramagnetic species in... more Electron Paramagnetic Resonance (EPR) technique is useful to quantify the paramagnetic species in any matrix. The unpaired electrons present in paramagnetic materials have non – zero spin value, have an associated spin magnetic moment. When such a system is subjected to an external magnetic field, electronic Zeeman splitting of ground level state occurs. On application of suitable stimulant microwave energy, the electrons flip between the Zeeman levels of ground state, result in resonant absorption of the microwave energy. The intensity of resonant absorption signal is proportional to the concentration of the unpaired electrons in the irradiated material, could lead to possible use of such materials in EPR dosimetric applications. New materials were investigated for EPR dosimetry, wherein the radiation induced paramagnetic species retains the radiation signatures, lead to idea on radiation dose. Few of the materials have been identified as prospective EPR dosimeters. The radiation i...

A brief account of the luminescence studies of gemstones ruby,chryso beryl and diamond are given ... more A brief account of the luminescence studies of gemstones ruby,chryso beryl and diamond are given The luminescence of ruby primarily arises due to trivalent chromium impurity, where as the nitrogen-vacancy complexex are the main centres of luminescence in diamond. In the case of diamond surface fluorescence mapping under deep UV excitation is invaluable in detecting the lab grown diamonds.

Superconductor …, 2001

... ofHc1 were obtained at different temperatures and the value of Hc1(0) is found to be 250 G. T... more ... ofHc1 were obtained at different temperatures and the value of Hc1(0) is found to be 250 G. The absorbed microwave power showed ... The authors wish to thank Dr SB Manohar, Head of the Radiochemistry Division, for his keen interest during the course of these investigations. ...

Nuclear Technology, 1989

Uranium-aluminum alloys with a significant enrichment of uranium with 233 U or 23SU serve as nucl... more Uranium-aluminum alloys with a significant enrichment of uranium with 233 U or 23SU serve as nuclear fuels in research reactors. The quality assurance of this fuel requires, among other things, precise knowledge that all trace metal constituents that affect neutron economy, fuel integrity, and fuel fabrication process parameters are well within the specification limits. Trace metal characterization of m U-Al alloy has been carried out by atomic spectrometry. The trace metal constituents of interest are grouped into common metals (

Bulletin of Materials Science, 2014

U 6+ doped BaSO 4 samples were synthesized by precipitation route. PL, TL and EPR investigations ... more U 6+ doped BaSO 4 samples were synthesized by precipitation route. PL, TL and EPR investigations of γ and self α irradiated samples were carried out. PL spectra of these samples give structured broad band peaking around 518 nm with five vibronic bands centred around 498•4, 516•0, 533•7, 554•0 and 575•1 nm, respectively and the average frequency of symmetric stretching of O=U=O in the ground electronic state was found to be 674 cm −1. Trap level spectroscopic studies of U doped BaSO 4 give glow peaks at 411, 488 and 512 K, respectively and their spectral characteristics are typical of UO 2+ 2 emission. EPR studies of γ-irradiated U 6+ :BaSO 4 sample have shown the presence of sulphoxy centred radicals like SO − 4 and SO − 3 in addition to OH • , O − 3 and SH 2−. TSL peaks at 411 and 488 K were correlated with thermal destruction of SO − 4 and SO − 3 radicals.

Philosophical Magazine B: Physics of Condensed Matter; Statistical Mechanics, Electronic, Optical and Magnetic Properties, 2001

With a view to investigating the nature of weak links in granular superconductors at very dilute ... more With a view to investigating the nature of weak links in granular superconductors at very dilute level, we have studied the low-field microwave absorption signal (below about 50 G) in the electron paramagnetic resonance mode of detection in samples of Tl2BaCa2Cu2O8+δ and YBa2CuO7-δ at different dilution levels in the AlO3 matrix. The signal has been monitored as a function of

Indian Journal of Physics, 2009

Ultrafine M 5 (PO 4) 3 F:Dy 3+ (M = Ca, Ba) phosphors were prepared via combustion process using ... more Ultrafine M 5 (PO 4) 3 F:Dy 3+ (M = Ca, Ba) phosphors were prepared via combustion process using metal nitrates as precursors. The formation of crystalline phosphate was confirmed by X-ray diffraction pattern. The PL excitation spectra show the excitation peaks observed at 250 to 400 nm due to f → f transition of Dy 3+ ion, which are useful for solid-state lighting purpose (mercury free excitation). The PL emission of Dy 3+ ion by 348 nm excitation gave an emission at 489 nm (blue), 582 nm (yellow) and 675 nm (red). All the characteristics of BYR emissions like BGR indicate that Dy doped Ca 5 (PO 4) 3 F and Ba 5 (PO 4) 3 F phosphors are good candidates that can be applied in solid-state lighting phosphor (mercury free excited lamp phosphor) and white light LED.

Journal of Physics D: Applied Physics, 2007

Thermoluminescence (TL), electron spin resonance (ESR) and x ray diffraction studies of CaSO4 : D... more Thermoluminescence (TL), electron spin resonance (ESR) and x ray diffraction studies of CaSO4 : Dy phosphor subjected to post preparation high temperature treatment were carried out. Analysis of the TL glow curve indicated that the dosimetric glow peak at 240 °C reduces, whereas the low temperature satellite peak increases with the increase in the annealing temperature in the range 650-1000

Journal of Experimental Nanoscience, 2013

White light emitting Sr 2 SiO 4 :Eu 2þ nanoparticles were prepared using reverse micellar route u... more White light emitting Sr 2 SiO 4 :Eu 2þ nanoparticles were prepared using reverse micellar route using Tergitol as a surfactant. The systems were characterised by X-ray diffraction, scanning electron microscopy (SEM), photoluminescence, thermoluminescence (TL), and electron paramagnetic resonance (EPR) spectroscopy. SEM shows the formation of silicate nanorods. Two emission bands of bluish-green at 490 nm (S(I)) and of orange-red at 605 nm (S(II)) were observed. The two emission bands are assigned to the 4f-5d transition of Eu 2þ ions in two different cation sites in a 0-Sr 2 SiO 4 orthorhombic lattices. Gammairradiated Sr 2 SiO 4 :Eu showed the presence of three TL glow peaks at 437, 487 K and weak peak at 540 K; however, no glow was observed in the undoped sample. Reduction of Eu 3þ to Eu 2þ is confirmed by EPR spectroscopy.

Applied Radiation and Isotopes, 2011

CaSO 4 :Dy, CaSO 4 :(Dy, Bi) and CaSO 4 :Bi phosphors were prepared through re-crystallization me... more CaSO 4 :Dy, CaSO 4 :(Dy, Bi) and CaSO 4 :Bi phosphors were prepared through re-crystallization method. Thermoluminescence (TL) characteristics of these phosphor samples were investigated. The radiation induced radical ions formed in these phosphors were investigated using electron paramagnetic resonance (EPR) spectroscopy. The main signals observed in both CaSO 4 :(Dy, Bi) and CaSO 4 :Bi were identified as SO À 4 (II), SO À 4 (?) and SO À 3 (isotropic) with ''g'' values 2.023, 2.0089 and 2.004, respectively. In order to understand the TL mechanism, CaSO 4 :(Dy, Bi) phosphor samples were annealed between 100 and 250 1C and their EPR spectra were studied. It was observed that EPR signal intensities reduce drastically in 250 1C annealed phosphor confirming the role of SO À 4 and SO À 3 types of defect centers in the dosimetric peak. The reduction in the TL sensitivity with increase in Bi 3 + co-dopant in the phosphor samples was correlated with quenching of TL by Bi 3 + ions rather than the reduction in the concentration of the above defect centers. An effort was also made to use the Bi 3 + co-doped CaSO 4 :Dy phosphor for dosimetry of chilled or frozen food irradiation.

Materials Letters, 2005

Systematic magnetic field dependent microwave absorption measurements have been performed on nano... more Systematic magnetic field dependent microwave absorption measurements have been performed on nanocrystalline La 0.6 Pb 0.4 MnO 3 (LPMO) thin films over a temperature range of 77–300 K. In addition to a regular ferromagnetic resonance (FMR) signal below the Curie ...

Nuclear technology

Uranium-aluminum alloys with a significant enrichment of uranium with ²³³U or ²³⁵U serve a... more Uranium-aluminum alloys with a significant enrichment of uranium with ²³³U or ²³⁵U serve as nuclear fuels in research reactors. The quality assurance of this fuel requires, among other things, precise knowledge that all trace metal constituents that affect neutron economy, fuel integrity, and fuel fabrication process parameters are well within the specification limits. Trace metal characterization of ²³⁵U-Al alloy has

Journal of the American Ceramic Society, 2014

ABSTRACT ThO2:Eu3+ nanoparticles were synthesized at 300°C by combustion route using urea as a fu... more ABSTRACT ThO2:Eu3+ nanoparticles were synthesized at 300°C by combustion route using urea as a fuel and characterized by thermogravimetric/differential thermal analysis, X-ray diffraction, transmission electron microscopy, and photoluminescence techniques. To investigate the effect of annealing temperature, as synthesized powder were heated further at 500°C, 700°C, and 900°C. It was observed that extent of asymmetry around Eu3+ at 700°C/900°C is very high as compared to as-prepared or 500°C annealed sample. Based on the time resolved emission spectroscopic investigations, it was inferred that two different types of Eu3+ ions were present in the ThO2 nanoparticles. In ThO2 structure, Eu3+ ions occupy two sites; cubic (Oh) and noncubic (<C2v) as can be confirmed from our emission studies. Short-lived species T1 (~1.3–3.4 ms) predominates at higher annealing temperature arises because of Eu3+ ions occupying noncubic (<C2v) sites without inversion symmetry, whereas long-lived species T2 (~4.6–6.6 ms) can be ascribed to Eu3+ ions occupying cubic sites (Oh) with inversion symmetry.

Indian Journal of Physics, 2009

Radiation Physics and Chemistry, 2010

Electron paramagnetic resonance (EPR) investigations of Li 2 C 2 O 4 , Na 2 C 2 O 4 mixed in prop... more Electron paramagnetic resonance (EPR) investigations of Li 2 C 2 O 4 , Na 2 C 2 O 4 mixed in proportion 1:0, 0:1, 1:1, 2:1 and 3:1 were carried out to measure the absorbed dose from photons and thermal neutrons in a mixed radiation field. A single line spectrum of CO 2 À radical anion centered around g ¼ 2.00457 0.0005 was obtained in the respective cases on gamma and neutron irradiation. Except Na 2 C 2 O 4 , other mixtures had shown increase in line width on neutron irradiation possibly due to relaxation effects. Of all combinations, the 2:1 mixture is the more sensitive material for gamma and thermal neutrons. Intensity of CO 2 À radical signal in 2:1 Li 2 C 2 O 4 :Na 2 C 2 O 4 mixture was found to be linear from 0.006 to 11 kGy for gamma and 40-1530 kGy for thermal neutron doses. Radical signal was found to be stable over a period of 300 days with marginal fading of less than 1 percent. Experimental results thus obtained suggest 2:1 Li 2 C 2 O 4 :Na 2 C 2 O 4 mixture as the potential neutron dosimeter for medium and high dose range.

Philosophical Magazine Part B, 1999

We report the synthesis, magnetic characteristics and electron paramagnetic resonance (EPR) data ... more We report the synthesis, magnetic characteristics and electron paramagnetic resonance (EPR) data on the new hexacyanometallate-based bimetallic molecular compound [Ni(pn)2]3 [FeCN6]2 12H2O, where pn 1,2-propanediamine, which shows bulk ferromagnetic order below 19K. It is a soft magnet exhibiting a rather weak hysteresis. The EPR spectra show a fine structure, characteristic of an S 3/2 state, in a very narrow temperature

Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, 2008

Eu-activated Y2O3 phosphors were prepared by combustion synthesis and also by precipitation techn... more Eu-activated Y2O3 phosphors were prepared by combustion synthesis and also by precipitation techniques. Photoluminescence and X-ray excited luminescence of prepared Y2O3:Eu phosphor, under two different techniques were compared and reported in this paper. Y2O3:Eu3+ phosphor were prepared by precipitation technique followed by annealing at 900°C. It gives cubic nature of the particle that may be more favourable for high lumen

Research on Chemical Intermediates, 2003

Absorption spectrophotometric studies indicated that in chloroform¯-carotene reacted with NO 2 wi... more Absorption spectrophotometric studies indicated that in chloroform¯-carotene reacted with NO 2 with a stoichiometry of 1 : 2. To understand the reaction mechanism, free radical intermediates produced during their reaction were trapped by spin traps 2-methyl-2-nitroso propane (MNP) and 4-pyridyl-1-oxide-N-1-but yl nitrone (POBN). The resulting stable spin adducts were detected by electron spin resonance (ESR) spectroscopy. NO 2 alone did not interact with spin traps, but introduction of¯-carotene-generatedESR signals with different nitrogen and hydrogen hyper ne coupling constants (A N and A H) characteristic of the trapped radical. Two possible pathways exist for the reaction of NO 2 with¯-carotene, viz., electron transfer and addition to the polyene chain. Our ESR results supported an addition mechanism, where formation of carbon-centered [NO 2 ¢ ¢ ¢¯-carotene] free radical adduct was observed.