http://pucir.inflibnet.ac.in:8080/jspui/handle/123456789/610 2026-04-30T23:17:52Z 2026-04-30T23:17:52Z Devi Victory, CH http://pucir.inflibnet.ac.in:8080/jspui/handle/123456789/615 2024-06-12T09:49:50Z 2023-01-01T00:00:00Z

Title: Luminescence properties of Ln3+ doped BaMoO4 (Ln3+ = Sm3+ and Dy3+) phosphors under UV excitation Authors: Devi Victory, CH Abstract: Ln3+ doped BaMoO4 (Ln 3+ = Sm3+ and Dy3+) nanoparticles have been synthesized successfully using ethylene glycol as a solvent. All the prepared samples are well indexed into the pure scheelite-type tetragonal structure of BaMoO4, the doping of trivalent ions (Ln3+) in to the bivalent host ions (Ba2+) sites of the BaMoO4 do not change the pure tetragonal structure of BaMoO4 although there is a charge difference between Ba2+ and Ln3+. The SEM image of the prepared BaMoO4 samples shows a number of uniform shuttle-like nanocrystalline with protrusion in the middle. The doping of Ln3+ ions do not change the morphology of the BaMoO4. The photoluminescence study has been carried in detail by measuring the excitation and emission spectra of the prepared samples. The excitation spectrum consists of a broad band with a maximum at about 268 nm thereby demonstrating the transfer of energy from MoO24 - groups to the doped Ln3+ ions. Yellow emission is dominated over blue in case of Dy3+ doped BaMoO4 and in Sm3+ doped BaMoO4 red emission dominated over other lights under UV excitation. The luminescence intensity is highest at 10 at.% Ln3+ under the UV excitation. Under this UV excitation BaMoO4: Sm3+ exhibits strong orange-red and BaMoO4:Dy3+ greenish-yellow emissions. Excitation of Dy3+ in thin film of BaMoO4 emits an intense yellow color which could be applicable in the field of biological assays and biological fluorescence labeling.

2023-01-01T00:00:00Z Devi Victory, CH http://pucir.inflibnet.ac.in:8080/jspui/handle/123456789/614 2024-06-12T09:45:16Z 2015-03-09T00:00:00Z

Title: Effect of annealing on the luminescence properties of YVO4:Dy3+ phosphor on co-doping Pb2+ ions Authors: Devi Victory, CH Abstract: Pb2+ co-doped YVO4:Dy3+ phosphors have been synthesized at a relatively low temperature of 120 C via ethylene glycol route. The samples are further annealed at 500 and 900 C. The prepared samples were characterized by XRD, SEM, spectra energy dispersive analysis of X-ray (EDAX) and photoluminescence spectroscopy. XRD patterns of all samples are well indexed with single tetragonal phase of YVO4. The emission intensity of Dy3+ is significantly enhanced on co-doping Pb2+ ions. The highest emission is obtained at 7 at.% Pb2+ for 900 C annealed samples. Both emission intensity and decay lifetime increases on annealing the samples from 500 to 900 C. On co-doping Pb2+ into YVO4:Dy3+ phosphors, the emission color falls near the white region and then shift towards yellow region on annealing from 500 to 900 C thereby indicating that annealing temperature play a role on tuning the color of the phosphors. As well as the emission color of the phosphors remain the same even on changing the excitation wavelengths from 280 nm, which would serve as potential phosphors for white emission in LED applications.

2015-03-09T00:00:00Z Devi Victory, CH http://pucir.inflibnet.ac.in:8080/jspui/handle/123456789/613 2024-06-12T09:42:44Z 2011-06-13T00:00:00Z

Title: Comparative absorption spectroscopy involving 4f–4f transitions to explore the kinetics of simultaneous coordination of uracil with Nd(III) and Zn(II) and its associated thermodynamics Authors: Devi Victory, CH Abstract: The interaction of uracil with Nd(III) has been explored in presence and absence of Zn(II) using the comparative absorption spectroscopy involving the 4f–4f transitions in different solvents. The complexation of uracil with Nd(III) is indicated by the change in intensity of 4f–4f bands expressing in terms of significant change in oscillator strength and Judd–Ofelt parameters. Intensification of this bands became more prominent in presence of Zn(II) suggesting the stimulative effect of Zn(II) towards the complexation of Nd(III) with uracil. Other spectral parameters namely Slator–Condon (Fk’s), nephelauxetic effect (ˇ), bonding (b1/2) and percent covalency (ı) parameters are computed to correlate their simultaneous binding of metal ions with uracil. The sensitivities of the observed 4f–4f transitions towards the minor coordination changes around Nd(III) has been used to monitor the simultaneous coordination of uracil with Nd(III) and Zn(II). The variation of intensities (oscillator strengths and Judd–Ofelt parameters) of 4f–4f bands during the complexation has helped in following the heterobimetallic complexation of uracil. Rate of complexation with respect to hypersensitive transition was evaluated. Energy of activation and thermodynamic parameters for the complexation reaction were also determined.

2011-06-13T00:00:00Z Devi Victory, CH http://pucir.inflibnet.ac.in:8080/jspui/handle/123456789/612 2024-06-12T09:40:02Z 2010-12-25T00:00:00Z

Title: Absorption spectroscopic probe to investigate the interaction between Nd(III) and calf-thymus DNA Authors: Devi Victory, CH Abstract: The interaction between Nd(III) and Calf Thymus DNA (CT-DNA) in physiological buffer (pH 7.4) has been studied using absorption spectroscopy involving 4f–4f transition spectra in different aquated organic solvents. Complexation with CT-DNA is indicated by the changes in absorption intensity following the subsequent changes in the oscillator strengths of different 4f–4f bands and Judd–Ofelt intensity (T ) parameters. The other spectral parameters namely Slator–Condon (Fk’s), nephelauxetic effect (ˇ), bonding (b1/2) and percent covalency (ı) parameters are computed to correlate with the binding of Nd(III) with DNA. The absorption spectra of Nd(III) exhibited hyperchromism and red shift in the presence of DNA. The binding constant, Kb has been determined by absorption measurement. The relative viscosity of DNA decreased with the addition of Nd(III). Thermodynamic parameters have been calculated according to relevant absorption data and Van’t Hoff equation. The characterisation of bonding mode has been studied in detail. The results suggested that the major interaction mode between Nd(III) and DNA was external electrostatic binding.

2010-12-25T00:00:00Z