The results of ESR investigations carried out on γ-irradiated Ag-doped lithium sodium sulphate (LiNaSO4) at LNT (77 K) are reported here. Two different centres of Ag (Ag0, Ag2+) have been observed at 77 K. In the case of Ag2+ the parameters are gxx=2.071±0.001, gyy=2.102±0.001, gzz=2.402±0.001, Axx=18±1 G, Ayy=20± 1 G,and Azz = 26 ± 1 G. The ground-state wave function has been found to be consist primarily of dx2-y2 with a reasonable admixture of other orbitals. The extent of delocalization of the electron in the Ag2+ has been estimated. For Ag0 the parameters g and A are found to be isotropic. © 1995.

K. Chandrasekharan

V. S. Murty

Doping (additives)

Electric fields

Electron energy levels

Electrons

Paramagnetic resonance

Silver

DELOCALIZATION

GROUND STATE WAVE FUNCTION

LITHIUM SODIUM SULFATE

PARAMAGNETIC CENTRES

Lithium compounds

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It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Radiation-induced paramagnetic silver centers in LiNaSO4

Physica B: Physics of Condensed Matter

Thermoluminescence (TL) studies have been carried out on CaSO 4 : Mn, CaSO 4 : Ag,Mn, CaSO 4 : Ag,Nd, CaSO 4 : Ag,Mn,Nd, CaSO 4 : Ag,Zr and CaSO 4 : Ag,Mn,Zr phosphors. It is found that TL at 360 °C in CaSO 4 : Ag,Mn,Nd is about 40 times that of CaSO 4 : Ag,Mn and about 170 times that of CaSO 4 : Ag,Nd. This shows that the presence of an efficient luminescent centre (Mn 2+) as well as a trivalent impurity (such as Nd 3+ or Y 3+) is important for enhancement of TL at 360 °C in the CaSO 4 : Ag,Mn,Nd phosphor system. Electron spin resonance (ESR) studies show that the peak at 360 °C correlates with an Ag 2+ centre formed due to γ-irradiation and observable only below -170 °C. The Ag 2+ centre is characterized by an axial g-tensor with principal values g ∥ = 2.38 and g ⊥ = 2.41. ESR studies further indicate that the precursor to a centre observable at low temperature (-170 °C) appears to act as the recombination centre for the TL peak at 360 °C. The low temperature centre is characterized by the g-values g ∥ = 2.0023 and g ⊥ = 2.0038 and is assigned to the radical. © 2006 IOP Publishing Ltd.

Journal of Physics D: Applied Physics

ESR and TL mechanism in CaSO 4 : AAAg co-doped phosphors

The defect centres formed in the TL phosphor CaSO4:Dy,Ag are studied using the technique of Electron Spin Resonance. The Ag co-doped phosphor exhibits three glow peaks around 130, 220 and 375°C in contrast with the two glow peaks observed in the CaSO4:Dy phosphor at 130 and 220°C at a gamma ray dose of 1Gy. ESR studies show that the additional peak at 375°C correlates with a Ag2+ centre formed due to gamma irradiation and observable only below -170°C. The Ag2+ centre is characterised by an axial g-tensor with principal values g∥ = 2.38 and g⊥ = 2.41. ESR studies further indicate that the precursor to a centre observable at low temperature (-170°C) appears to act as the recombination centre for the TL peak at 375°C; this radical is characterised by the g-values g∥ = 2.0023 and g⊥ = 2.0038 and is assigned to SO3- radical. It is observed that there is more incorporation of Ag in the CaSO4:Dy system as compared with that in pure CaSO4 system. © 2006 Oxford University Press.

Radiation Protection Dosimetry

Defect centres and thermoluminescence in CaSO4:Dy,Ag phosphor

The defect centres formed in the thermoluminescence (TL) phosphor CaSO 4 : Dy,Ag are studied using the technique of electron spin resonance (ESR). The Ag co-doped phosphor exhibits three glow peaks around 130°C, 220°C and 375°C, in contrast to the two glow peaks observed in the CaSO4 : Dy phosphor at 130°C and 220°C, at gamma ray dose of 1 Gy when the TL measurements were carried out in the spectral region 300-650 nm. ESR studies show that the additional peak at 375°C correlates with a Ag2+ centre formed owing to γ-irradiation and observable below -170°C. The Ag2+ centre is characterized by an axial g-tensor with principal values g| ≤ 2.38 and g∥ ≤ 2.41. ESR studies further indicate that the precursor to a centre observable at low temperature (-170°C) appears to act as the recombination centre for the TL peak at 375°C; this radical is characterized by the g-values g| ≤ 2.0023 and g∥ ≤ 2.0038 and is assigned to the radical. It is observed that there is more incorporation of Ag in the CaSO4 : Dy system as compared with that in the pure CaSO4 system. The variation of Ag2 + ESR intensity with Ag concentration as well as with dose in the range 0.3-120 kGy is studied. The Ag2 + ESR signal and TL saturate at 2 × 104 Gy, but the intensity of the radical continues to increase up to the studied dose of 1.2 × 105 Gy. The intensity of the radical decreases with Ag concentration in CaSO4 : Dy,Ag, in agreement with the TL model proposed in this work. © 2005 IOP Publishing Ltd.

Electron spin resonance and thermoluminescence studies in CaSO4: Dy,Ag phosphor

Single crystal E.P.R. Of Cu(II) in a very low symmetry ligand field is reported. The63Cu hyperfine and g factors are found to be orthorhombic with gxx = 2.1009, gyy = 2.0811, gzz = 2.3919, Axx = 21-4 ± 0-4, Ayy = 10-0 ±0-4, Azz = 108.0 ± 0.1 × 10-4cm-1. The magnitude of the principal values of the hyperfine tensor is one of the lowest ever reported for Cu(II) and is rationalized in terms of a mixed dx2-y2/dz2 ground state. The 20 K optical bands have been assigned based on RT polarization characteristics and assuming Cs symmetry for convenience. © 1986 Taylor &amp; Francis Group, LLC.

Molecular Physics

E.P.R. Of cu(II) in dinitratobis(antipyrine)zinc(II) single crystals: A case of low symmetry and mixed ground state

Journal of Physics: Condensed Matter

Electronic structure of Ag2+impurities in halide lattices

How do the electronic properties of d9impurities depend on metal-ligand distances? Application to Ni+, Cu2+and Ag2+systems

Journal of the Physical Society of Japan

ESR Study of Low Temperature Phase Transitions in Se Doped LiKSO4

Physica B+C

Evaluation of anisotropic non-coincident g and A tensors from EPR and endor data by the method of least-squares fitting

Journal	Physica B: Physics of Condensed Matter
ISSN	09214526
Open Access	No