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Tyagi A, Nigam S, Sudarsan V, Majumder C, Vatsa RK, Tyagi AK. Why Do Relative Intensities of Charge Transfer and Intra-4f Transitions of Eu 3+ Ion Invert in Yttrium Germanate Hosts? Unravelling the Underlying Intricacies from Experimental and Theoretical Investigations. Inorg Chem 2020; 59:12659-12671. [PMID: 32845617 DOI: 10.1021/acs.inorgchem.0c01757] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The dominant intensity of parity-forbidden intra-4f transitions of europium(III) over O → Eu charge-transfer band (CTB) intensity is against common perceptions, yet this trend is observed in many germanate hosts and has not been rationalized so far. In search of a plausible explanation for this unusual trend, present work reports an experimental and theoretical investigations in conjunction on two sibling germanate host, namely, Y2GeO5 and Y2Ge2O7 having dopant Eu3+ in their respective YO7 polyhedra. Whereas for Y2GeO5:Eu3+, the CTB is more intense than the intra-4f transitions in the excitation spectrum, in the case of Y2Ge2O7:Eu3+, the relative intensities of CTB and intra-4f transitions are reversed. Comparative structural analysis reveals that Eu3+ present in YO7 of Y2GeO5 has a greater number of tetra-coordinated oxygen (Otetra) and yttrium atom as first and second neighbors, respectively (Eu3+-Otetra-Y3+ linkages). Conversely, in Y2Ge2O7 host, the Eu3+ ion mostly has tricoordinated oxygen (Otri) as its nearest neighbor and germanium ions next to Otri (Eu3+-Otri-Ge4+ linkage). Theoretical calculations reveal that while Y2GeO5:Eu has Otetra(4Y) dominating at the Fermi level and the 4f state of Eu3+ remains inert toward mixing, in Y2Ge2O7:Eu, the Fermi level has major contribution from Otri(2Y + 1Ge) with significant mixing with 4f states of Eu. The dominant control of Eu3+-Otri-Ge4+ linkages in geometrical and electronic structure of Y2Ge2O7:Eu owing to the GeO4 surrounding has been attributed to relative poor intensity of O → Eu CTB. Siege of Eu3+ by GeO4 and subsequent occurrence of Eu3+-Otri-Ge4+ linkages play a dual role: First, it induces electronic rigidity to hinder excitation of electron at bridging (Otri) oxygen by highly charged small Ge4+ cation; second, the covalent character in Eu-O bond is achieved by intermixing of Eu's 4f and Otri 2p orbital which facilitates relaxing of the parity-selection rule thus enhancing the probability of intra-4f transitions. The inferences drawn remain valid when extrapolated to other inorganic oxides having EuOx polyhedra surrounded by covalent units like PO4, SiO4, etc. and have a prevailing number of low-coordinated oxygen atoms and highly charged small cation in the first and second coordination shells, respectively. The optical basicity concept is also found to endorse our explanation. These remarkable generic inferences will pave the rational way for designing efficient phosphors for solid-state lighting.
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Affiliation(s)
- Adish Tyagi
- Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085 India.,Homi Bhabha National Institute (HBNI), Mumbai 400 094, India
| | - Sandeep Nigam
- Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085 India.,Homi Bhabha National Institute (HBNI), Mumbai 400 094, India
| | - V Sudarsan
- Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085 India.,Homi Bhabha National Institute (HBNI), Mumbai 400 094, India
| | - C Majumder
- Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085 India.,Homi Bhabha National Institute (HBNI), Mumbai 400 094, India
| | - R K Vatsa
- Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085 India.,Homi Bhabha National Institute (HBNI), Mumbai 400 094, India
| | - A K Tyagi
- Chemistry Division, Bhabha Atomic Research Center, Mumbai 400 085 India.,Homi Bhabha National Institute (HBNI), Mumbai 400 094, India
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2
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Sharma KS, Ningthoujam RS, Dubey AK, Chattopadhyay A, Phapale S, Juluri RR, Mukherjee S, Tewari R, Shetake NG, Pandey BN, Vatsa RK. Synthesis and characterization of monodispersed water dispersible Fe 3O 4 nanoparticles and in vitro studies on human breast carcinoma cell line under hyperthermia condition. Sci Rep 2018; 8:14766. [PMID: 30283083 PMCID: PMC6170485 DOI: 10.1038/s41598-018-32934-w] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 08/30/2018] [Indexed: 11/21/2022] Open
Abstract
Monodispersed Fe3O4 magnetic nanoparticles (MNPs) having size of 7 nm have been prepared from iron oleate and made water dispersible by functionalization for biomedical applications. Three different reactions employing thioglycolic acid, aspartic acid and aminophosphonate were performed on oleic acid coated Fe3O4. In order to achieve a control on particle size, the pristine nanoparticles were heated in presence of ferric oleate which led to increase in size from 7 to 11 nm. Reaction parameters such as rate of heating, reaction temperature and duration of heating have been studied. Shape of particles was found to change from spherical to cuboid. The cuboid shape in turn enhances magneto-crystalline anisotropy (Ku). Heating efficacy of these nanoparticles for hyperthermia was also evaluated for different shapes and sizes. We demonstrate heat generation from these MNPs for hyperthermia application under alternating current (AC) magnetic field and optimized heating efficiency by controlling morphology of particles. We have also studied intra-cellular uptake and localization of nanoparticles and cytotoxicity under AC magnetic field in human breast carcinoma cell line.
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Affiliation(s)
- K S Sharma
- Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - R S Ningthoujam
- Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India.
| | - A K Dubey
- Bio-organic Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - A Chattopadhyay
- Bio-organic Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - S Phapale
- Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - R R Juluri
- Institute of Physics, SachivalayaMarg, Bhubaneswar, 751005, India
| | - S Mukherjee
- UGC-DAE Consortium for Scientific Research, Mumbai Centre, Mumbai, 400085, India
| | - R Tewari
- Material Science Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - Neena G Shetake
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - B N Pandey
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
| | - R K Vatsa
- Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400085, India
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Barick KC, Sharma A, Shetake NG, Ningthoujam RS, Vatsa RK, Babu PD, Pandey BN, Hassan PA. Covalent bridging of surface functionalized Fe3O4 and YPO4:Eu nanostructures for simultaneous imaging and therapy. Dalton Trans 2016. [PMID: 26215789 DOI: 10.1039/c5dt01522g] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Magnetic luminescent hybrid nanostructures (MLHN) have received a great deal of attention due to their potential biomedical applications such as thermal therapy, magnetic resonance imaging, drug delivery and intracellular imaging. We report the development of bifunctional Fe3O4 decorated YPO4:Eu hybrid nanostructures by covalent bridging of carboxyl PEGylated Fe3O4 and amine functionalized YPO4:Eu particles. The surface functionalization of individual nanoparticulates as well as their successful conjugation was evident from Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), zeta-potential and transmission electron microscopy (TEM) studies. X-ray diffraction (XRD) analysis reveals the formation of highly crystalline hybrid nanostructures. TEM micrographs clearly show the binding/anchoring of 10 nm Fe3O4 nanoparticles onto the surface of 100-150 nm rice grain shaped YPO4:Eu nanostructures. These MLHN show good colloidal stability, magnetic field responsivity and self-heating capacity under an external AC magnetic field. The induction heating studies confirmed localized heating of MLHN under an AC magnetic field with a high specific absorption rate. Photoluminescence spectroscopy and fluorescence microscopy results show optical imaging capability of MLHN. Furthermore, successful internalization of these MLHN in the cells and their cellular imaging ability are confirmed from confocal microscopy imaging. Specifically, the hybrid nanostructure provides an excellent platform to integrate luminescent and magnetic materials into one single entity that can be used as a potential tool for hyperthermia treatment of cancer and cellular imaging.
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Affiliation(s)
- K C Barick
- Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India.
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Nair RG, Nigam S, Vishwanadh B, Sudarsan V, Vatsa RK, Majumder C, Jain VK. Size induced modification of boron structural unit in YBO3: systematic investigation by experimental and theoretical methods. RSC Adv 2016. [DOI: 10.1039/c6ra12704e] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Nanocrystalline YBO3 (∼4–8 nm) was prepared using polyol method. It is established that while bulk YBO3 has only BO4 units, its nanoparticles has both BO3 and BO4 units. The BO3 units are primarily distributed on surface on nanoparticles.
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Affiliation(s)
| | - Sandeep Nigam
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400 085
- India
| | - B. Vishwanadh
- Material Science Division
- Bhabha Atomic Research Centre
- Mumbai 400 085
- India
| | - V. Sudarsan
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400 085
- India
| | - R. K. Vatsa
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400 085
- India
| | | | - V. K. Jain
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai 400 085
- India
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Sanap KK, Varma S, Waghmode SB, Sharma P, Manoj N, Vatsa RK, Bharadwaj SR. Bimetallic Wiregauze Supported Pt-Ru Nanocatalysts for Hydrogen Mitigation. J Nanosci Nanotechnol 2015; 15:3522-3529. [PMID: 26504972 DOI: 10.1166/jnn.2015.9862] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Passive autocatalytic recombiner (PAR) is one of the most suitable devices for mitigation of hydrogen, generated in nuclear power plant under accidental conditions. For this purpose we report development of stainless steel wire gauze supported Pt-Ru nanoparticles as catalysts. Simultaneous electroless deposition has been employed for the synthesis of the catalysts. Pt-Ru based bimetallic catalysts were characterized for their rate of coating kinetics, noble metal loading, phase purity by XRD and surface morphology by SEM, TEM and elemental analysis by SIMS. Developed catalysts were found to be active for efficient recombination of hydrogen and oxygen in air as well as in presence of various prospective poisons like CO2, CH4, CO and relative humidity. Pt-Ru based bimetallic catalyst with 0.9% loading was found to be active for CO poisoning up to 400 ppm of CO.
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Ningthoujam RS, Sharma A, Sharma KS, Barick KC, Hassan PA, Vatsa RK. Roles of solvent, annealing and Bi3+ co-doping on the crystal structure and luminescence properties of YPO4:Eu3+ nanoparticles. RSC Adv 2015. [DOI: 10.1039/c5ra11587f] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
There are roles of solvent, annealing and Bi3+ co-doping on crystal structure and luminescence properties of YPO4:Eu3+ nanoparticles.
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Affiliation(s)
| | - Anusha Sharma
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - K. S. Sharma
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - K. C. Barick
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - P. A. Hassan
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
| | - R. K. Vatsa
- Chemistry Division
- Bhabha Atomic Research Centre
- Mumbai-400085
- India
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Basu S, Sanyasi Naidu B, Viswanadh B, Sudarsan V, Jha SN, Bhattacharyya D, Vatsa RK. Nature of WO4 tetrahedra in blue light emitting CaWO4 probed through the EXAFS technique. RSC Adv 2014. [DOI: 10.1039/c3ra47619g] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Jadhav NV, Prasad AI, Kumar A, Mishra R, Dhara S, Babu KR, Prajapat CL, Misra NL, Ningthoujam RS, Pandey BN, Vatsa RK. Synthesis of oleic acid functionalized Fe3O4 magnetic nanoparticles and studying their interaction with tumor cells for potential hyperthermia applications. Colloids Surf B Biointerfaces 2013; 108:158-68. [PMID: 23537834 DOI: 10.1016/j.colsurfb.2013.02.035] [Citation(s) in RCA: 70] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Revised: 02/12/2013] [Accepted: 02/22/2013] [Indexed: 11/19/2022]
Abstract
In the present study, oleic acid (OA) functionalized Fe3O4 magnetic nanoparticles (MN) were synthesized following modified wet method of MN synthesis. The optimum amount of OA required for capping of MN and the amount of bound and unbound/free OA was determined by thermogravimetric analysis (TGA). Further, we have studied the effect of water molecules, associated with MN, on the variation in their induction heating ability under alternating current (AC) magnetic field conditions. We have employed a new approach to achieve dispersion of OA functionalized MN (MN-OA) in aqueous medium using sodium carbonate, which improves their biological applicability. Interactions amongst MN, OA and sodium carbonate were studied by Fourier transform infrared spectroscopy (FT-IR). Intracellular localization of MN-OA was studied in mouse fibrosarcoma cells (WEHI-164) by prussian blue staining and confocal laser scanning microscopy (CLSM) using nile blue A as a fluorescent probe. Results showed MN-OA to be interacting mainly with the cell membrane. Their hyperthermic killing ability was evaluated in WEHI-164 cells by trypan blue method. Cells treated with MN-OA in combination with induction heating showed decreased viability as compared to respective induction heating controls. These results were supported by altered cellular morphology after treatment of MN-OA in combination with induction heating. Further, the magnitude of apoptosis was found to be ~5 folds higher in cells treated with MN-OA in combination with induction heating as compared to untreated control. These results suggest the efficacy of MN-OA in killing of tumor cells by cellular hyperthermia.
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Affiliation(s)
- Neena V Jadhav
- Radiation Biology and Health Sciences Division, Bhabha Atomic Research Centre, Mumbai 400085, India
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9
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Shah A, Tyagi A, Naidu BS, Sudarsan V, Vatsa RK, Jain VK. Structural differences in the luminescence properties of lanthanide doped orthorhombic and monoclinic phases of Y2GeO5. RSC Adv 2013. [DOI: 10.1039/c3ra41953c] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Prasad AI, Parchur AK, Juluri RR, Jadhav N, Pandey BN, Ningthoujam RS, Vatsa RK. Bi-functional properties of Fe3O4@YPO4:Eu hybrid nanoparticles: hyperthermia application. Dalton Trans 2013; 42:4885-96. [DOI: 10.1039/c2dt32508j] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Shanta Singh N, Ningthoujam RS, Phaomei G, Singh SD, Vinu A, Vatsa RK. Re-dispersion and film formation of GdVO4 : Ln3+ (Ln3+ = Dy3+, Eu3+, Sm3+, Tm3+) nanoparticles: particle size and luminescence studies. Dalton Trans 2012; 41:4404-12. [PMID: 22334276 DOI: 10.1039/c2dt12190e] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
GdVO(4) : Ln(3+) (Ln(3+) = Dy(3+), Eu(3+), Sm(3+), Tm(3+)) nanoparticles are prepared by a simple chemical route at 140 °C. The crystallite size can be tuned by varying the pH of the reaction medium. Interestingly, the crystallite size is found to increase significantly when pH increases from 6 to 12. This is related to slower nucleation of the GdVO(4) formation with increase of VO(4)(3-) present in solution. The luminescence study shows an efficient energy transfer from vanadate absorption of GdVO(4) to Ln(3+) and thereby enhanced emissions are obtained. A possible reaction mechanism at different pH values is suggested in this study. As-prepared samples are well dispersed in ethanol, methanol and water, and can be incorporated into polymer films. Luminescence and its decay lifetime studies confirm the decrease in non-radiative transition probability with the increase of heat treatment temperature. Re-dispersed particles will be useful in potential applications of life science and the film will be useful in display devices.
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Affiliation(s)
- N Shanta Singh
- Department of Physics, Manipur University, Canchipur, Imphal-795003, Manipur, India
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12
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Patel DK, Rajeswari B, Sudarsan V, Vatsa RK, Kadam RM, Kulshreshtha SK. Structural, luminescence and EPR studies on SrSnO3 nanorods doped with europium ions. Dalton Trans 2012; 41:12023-30. [DOI: 10.1039/c2dt30691c] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Das S, Badani PM, Sharma P, Vatsa RK, Das D, Majumder A, Das AK. Multiphoton ionization and Coulomb explosion of C2H5Br clusters: a mass spectrometric and charge density study. Rapid Commun Mass Spectrom 2011; 25:1028-1036. [PMID: 21452379 DOI: 10.1002/rcm.4951] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 01/20/2011] [Accepted: 01/22/2011] [Indexed: 05/30/2023]
Abstract
Using time-of-flight mass spectrometry (TOFMS), laser-induced photochemistry of ethyl bromide clusters has been investigated at three different wavelengths (viz. 266, 355 and 532 nm) utilizing nanosecond laser pulses of ~5 × 10(9) W/cm(2). An interesting finding of the present work is the observation of multiply charged atomic ions of carbon and bromine at 355 and 532 nm, arising from the Coulomb explosion of (C(2)H(5)Br)(n) clusters. At 266 nm, however, the (C(2)H(5)Br)(n) clusters were found to exhibit the usual multiphoton dissociation/ionization behaviour. The TOFMS studies are complemented by measuring the total charge density of the ionized volume at 266, 355 and 532 nm, using the parallel plate method, and the charge densities were found to be ~2 × 10(9), 6 × 10(9) and 2 × 10(11) charges/cm(3), respectively. The significantly higher charge density and the presence of energetic, multiply charged atomic ions at 532 nm are explained by the higher ponderomotive energy of the 532 nm photon, coupled with the Coulomb stability of the residual multiply charged ethyl bromide clusters generated upon laser irradiation, due to their larger effective cluster size at 532 nm than at 355 and 266 nm.
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Affiliation(s)
- S Das
- Chemistry Division, Bhabha Atomic Research Centre, Mumbai, 400 085, India
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Luwang MN, Ningthoujam RS, Srivastava SK, Vatsa RK. Disappearance and Recovery of Luminescence in Bi3+, Eu3+ Codoped YPO4 Nanoparticles Due to the Presence of Water Molecules Up to 800 °C. J Am Chem Soc 2011; 133:2998-3004. [DOI: 10.1021/ja1092437] [Citation(s) in RCA: 132] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M. Niraj Luwang
- Department of Chemistry, Manipur University, Imphal-795003, India
| | - R. S. Ningthoujam
- Chemistry Division, Bhabha Atomic Research Center, Mumbai-400085, India
| | - S. K. Srivastava
- Department of Chemistry, Manipur University, Imphal-795003, India
| | - R. K. Vatsa
- Chemistry Division, Bhabha Atomic Research Center, Mumbai-400085, India
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Phaomei G, Ningthoujam RS, Singh WR, Loitongbam RS, Singh NS, Rath A, Juluri RR, Vatsa RK. Luminescence switching behavior through redox reaction in Ce3+ co-doped LaPO4:Tb3+ nanorods: Re-dispersible and polymer film. Dalton Trans 2011; 40:11571-80. [DOI: 10.1039/c1dt11264c] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ghosh R, Pradhan L, Devi YP, Meena SS, Tewari R, Kumar A, Sharma S, Gajbhiye NS, Vatsa RK, Pandey BN, Ningthoujam RS. Induction heating studies of Fe3O4 magnetic nanoparticles capped with oleic acid and polyethylene glycol for hyperthermia. ACTA ACUST UNITED AC 2011. [DOI: 10.1039/c1jm10092k] [Citation(s) in RCA: 268] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Hanf A, Volpp HR, Sharma P, Mittal JP, Vatsa RK. Ultraviolet photochemistry of buta-1,3- and buta-1,2-dienes: Laser spectroscopic absolute hydrogen atom quantum yield and translational energy distribution measurements. J Chem Phys 2010; 133:024308. [DOI: 10.1063/1.3462951] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Luwang MN, Ningthoujam RS, Srivastava SK, Vatsa RK. Effects of Ce3+ Codoping and Annealing on Phase Transformation and Luminescence of Eu3+-Doped YPO4 Nanorods: D2O Solvent Effect. J Am Chem Soc 2010; 132:2759-68. [DOI: 10.1021/ja909578s] [Citation(s) in RCA: 151] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- M. Niraj Luwang
- Department of Chemistry, Manipur University, Imphal-795003, India, and Chemistry Division and Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Center, Mumbai-400085, India
| | - R. S. Ningthoujam
- Department of Chemistry, Manipur University, Imphal-795003, India, and Chemistry Division and Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Center, Mumbai-400085, India
| | - S. K. Srivastava
- Department of Chemistry, Manipur University, Imphal-795003, India, and Chemistry Division and Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Center, Mumbai-400085, India
| | - R. K. Vatsa
- Department of Chemistry, Manipur University, Imphal-795003, India, and Chemistry Division and Technical Physics and Prototype Engineering Division, Bhabha Atomic Research Center, Mumbai-400085, India
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Rao CM, Sudarsan V, Ningthoujam RS, Gautam UK, Vatsa RK, Vinu A, Tyagi AK. Luminescence studies on low temperature synthesized ZnGa2O4:Ln3+ (Ln = Tb and Eu) nanoparticles. J Nanosci Nanotechnol 2008; 8:5776-5780. [PMID: 19198304 DOI: 10.1166/jnn.2008.246] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
ZnGa2O4 nanoparticles doped with lanthanide ions (Tb3+ and Eu3+) were prepared at a low temperature of 120 degrees C based on urea hydrolysis in ethylene glycol medium. X-ray diffraction studies have confirmed that strain associated with nanoparticles changes as Tb3+ gets incorporated in the ZnGa2O4 lattice. Based on steady state emission and excitation studies of ZnGa2O4:Tb nanoparticles, it has been inferred that ZnGa2O4 host is characterized by a broad emission around 427 nm and there exists energy transfer between the host and Tb3+ ions. Unlike this, for ZnGa2O4:Eu nanoparticles, very poor energy transfer between the host and Eu3+ ions is observed. These nanoparticles when coated with ligands like oleic acid results in their improved dispersion in organic solvents like chloroform and dichloromethane.
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Affiliation(s)
- C Manikyala Rao
- School of Chemistry, Andhra University, Visakhapatnam 530003, India
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Ningthoujam RS, Umare SS, Sharma SJ, Shukla R, Kurian S, Vatsa RK, Tyagi AK, Tewari R, Dey GK, Gajbhiye NS. Magnetic and Mössbauer studies on nanocrystalline Co1−x Li x Fe2O4 (x = 0, 0.2). ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s10751-008-9794-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Mukherjee S, Sudarsan V, Vatsa RK, Godbole SV, Kadam RM, Bhatta UM, Tyagi AK. Effect of structure, particle size and relative concentration of Eu(3+) and Tb(3+) ions on the luminescence properties of Eu(3+) co-doped Y(2)O(3):Tb nanoparticles. Nanotechnology 2008; 19:325704. [PMID: 21828826 DOI: 10.1088/0957-4484/19/32/325704] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Eu(3+) co-doped Y(2)O(3):Tb nanoparticles were prepared by the combustion method and characterized for their structural and luminescence properties as a function of annealing temperatures and relative concentration of Eu(3+) and Tb(3+) ions. For Y(2)O(3):Eu,Tb nanoparticles annealed at 600 and 1200 °C, variation in the relative intensity of excitation transitions between the (7)F(6) ground state and low spin and high spin 4f(7)5d(1) excited states of Tb(3+) is explained due to the combined effect of distortion around Y(3+)/Tb(3+) in YO(6)/TbO(6) polyhedra and the size of the nanoparticles. Increase in relative intensity of the 285 nm peak (spin-allowed transition denoted as peak B) with respect to the 310 nm peak (spin-forbidden transition denoted as peak A) with decrease of Tb(3+) concentration in the Y(2)O(3):Eu,Tb nanoparticles heated at 1200 °C is explained based on two competing effects, namely energy transfer from Tb(3+) to Eu(3+) ions and quenching among the Tb(3+) ions. Back energy transfer from Tb(3+) to Eu(3+) in these nanoparticles is found to be very poor.
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Affiliation(s)
- S Mukherjee
- Chemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085, India
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Sharma P, Vatsa RK, Kulshreshtha SK, Jha J, Mathur D, Krishnamurthy M. Energy pooling in multiple ionization and Coulomb explosion of clusters by nanosecond-long, megawatt laser pulses. J Chem Phys 2006; 125:34304. [PMID: 16863347 DOI: 10.1063/1.2217370] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
We report the results of experiments that establish the possibility of bringing about multiple ionization and Coulomb explosion of molecular clusters with nanosecond laser pulses at intensities as small as 10(9) W cm(-2). We demonstrate several new facets of the laser-cluster interaction in the low-intensity, long-pulse domain: (i) The choice of laser wavelength for a given cluster species is very crucial. (ii) Excited electronic states play a very important role in the ionization dynamics. (iii) When field ionization is insignificant and ponderomotive energies are very small, it is energy pooling rather than inverse bremsstrahlung that determines how clusters absorb energy from the optical field.
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Affiliation(s)
- P Sharma
- Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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Brownsword RA, Laurent T, Maity DK, Vatsa RK, Volpp HR. The reaction ND(a1 δ) + H2: laser spectroscopic measurement of room-temperature rate constant and H/D atom product branching ratio. Res Chem Intermed 2005. [DOI: 10.1163/1568567053146931] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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Sharma P, Vatsa RK, Rajasekhar BN, Das NC, Ghanty TK, Kulshreshtha SK. Photoionization of CH(3)I mediated by the C state in the visible and ultraviolet regions. Rapid Commun Mass Spectrom 2005; 19:1522-8. [PMID: 15880668 DOI: 10.1002/rcm.1951] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Three/two-photon resonant multiphoton ionization (MPI) of the CH3I monomer has been studied in the gas phase at 532 and 355 nm using time-of-flight mass spectrometry. Under low laser intensity (approximately 10(9) W/cm2) the mass spectra showed peaks at m/z 15, 127 and 142, corresponding to [CH3]+, [I]+ and [CH3I]+ species, at both these wavelengths. The laser power dependence for [CH3I]+, [I]+ and [CH3]+ ions showed a three-photon dependence at 532 nm. For the same three ions, photoionization studies at 355 nm gave a power dependence of 2. Both these results suggest that a vibronic energy level at approximately 7 eV, lying in the Rydberg C state, acts as a resonant intermediate level in ionization of CH3I. In the case of 355 nm, with increasing intensity additional peaks at m/z 139 and 141 were observed which could be assigned to [CI]+ and [CH2I]+ fragments. In contrast, for high intensity radiation at 532 nm ( approximately 2 x 10(10) W/cm2), only the [CI]+ fragment was observed. At these wavelengths, fragment ions observed in mass spectra mainly arise from photodissociation of the parent ion. Experiments at another wavelength in the visible region (564.2 nm) confirmed the results obtained at 532 nm. In order to assess the role of the A state in these MPI experiments, additional experiments were performed at 266 and 282.1 nm, which access the A state directly via a one-photon transition, and showed absence of a surviving precursor ion. Reaction energies for various possible dissociation channels of CH3I/[CH3I]+/[CH2I]+ were calculated theoretically at the MP2 level using the GAMESS electronic structure program.
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Affiliation(s)
- P Sharma
- Novel Materials and Structural Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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Sharma P, Vatsa RK, Maity DK, Kulshreshtha SK. Multiphoton dissociation/ionization of CHCl3 and CFCl3 at 355 nm: an experimental and theoretical study. Rapid Commun Mass Spectrom 2004; 18:2383-2387. [PMID: 15386631 DOI: 10.1002/rcm.1638] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Nonresonant laser-induced multiphoton dissociation/ionization studies have been conducted for trichloromethane (CHCl3) and trichlorofluoromethane (CFCl3) at 355 nm, using time-of-flight mass spectrometry (TOFMS). The molecular ion signal was found to be missing for both these compounds, and very similar fragmentation patterns were observed. Ab initio molecular electronic structure calculations were performed to help understand the fragmentation pattern of these molecules in the laser field. The energetics of different dissociation channels in the ground states of [CHCl3]+*, [CHCl2]+, [CFCl3]+* and [CFCl2]+, as well as neutral CHCl3, CHCl2*, CFCl3 and CFCl2* systems, were calculated. On comparing theoretical results with experimentally observed ion signals and their relative abundances in TOFMS, it is inferred that these molecules undergo sequential Cl atom elimination followed by photoionization of the fragments. The absence of [CFCl]+ has been interpreted on the basis of resonant A state-mediated two-photon absorption by CFCl, and the subsequent prompt photodissociation processes occurring for this state.
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Affiliation(s)
- P Sharma
- Novel Materials & Structural Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400 085, India
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Brownsword RA, Hillenkamp M, Laurent T, Volpp HR, Wolfrum J, Vatsa RK, Yoo HS. H atom formation dynamics in the dissociation of CH3–CF2Cl (HCFC-142b) after UV and VUV laser photoexcitation. J Chem Phys 1997. [DOI: 10.1063/1.474376] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
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Brownsword RA, Laurent T, Hillenkamp M, Vatsa RK, Volpp HR. Dissociation dynamics of HNCO and DNCO after laser photoexcitation in the vacuum ultraviolet. J Chem Phys 1997. [DOI: 10.1063/1.473857] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
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Brownsword RA, Hillenkamp M, Laurent T, Vatsa RK, Volpp HR. Photodissociation dynamics in the UV laser photolysis of DNCO: Comparison with HNCO. J Chem Phys 1997. [DOI: 10.1063/1.473489] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Brownsword RA, Hillenkamp M, Laurent T, Vatsa RK, Volpp HR, Wolfrum J. Photodissociation dynamics of the chloromethanes at the Lyman-α wavelength (121.6 nm). J Chem Phys 1997. [DOI: 10.1063/1.473304] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
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Dhanya S, Kumar A, Vatsa RK, Saini RD, Mittal JP, Pola J. Time-resolved study of the transients produced in the CO2 and ArF laser flash photolysis of gaseous silacyclobutane and 1,3-disilacyclobutane. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/ft9969200179] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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