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Dive into the research topics where B. Nandi Ganguly is active.

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Featured researches published by B. Nandi Ganguly.


Journal of Materials Science | 1996

Study of transition metal ion doped mullite by positron annihilation techniques

D. Sanyal; D. Banerjee; Rangalal Bhattacharya; S. K. Patra; S. P. Chaudhuri; B. Nandi Ganguly; U. De

Mullite, an extremely useful ceramic material, is doped with transition metal ions. The changes in the electronic properties of these doped materials have been studied by positron annihilation lifetime spectroscopy as well as Doppler broadened line shape analysis. The results on the positron annihilation parameters are characteristic of ionic size, oxidation state and the “d”-electron configuration of the respective transition metals doped in the parent lattice of the mullite. These results, along with the resistivity measurements are suggestive of transition of the parent mullite from an insulator to a semimetal in the modified structure.


Radiation Physics and Chemistry | 1996

Study of Triton X-100 surfactant-UO2+2 aqueous system by positron annihilation technique

Subir Kumar Das; B. Nandi Ganguly

Abstract Positron annihilation parameters have been used as a chemical probe to study the microphase transitional behaviour and microstructural changes in the aqueous surfactant system of Triton X-100. The interactions of positronium atom (Ps) in the system are discussed in the presence of a polar solubilizate e.g. UO2+2, in terms of the kinetic model. From this investigation, the microenvironment of UO2+2 is elucidated. An independent fluorescence spectroscopic assay of the UO2+2 ions in the micellar phase was made. These findings corroborate the information drawn from positron annihilation data.


Materials Research Bulletin | 1997

Effect of temperature on the synthesis of FeCl3-doped polypyrroles studied by positron annihilation technique

V. S. Subrahmanyam; Subir Kumar Das; B. Nandi Ganguly; A. Bhattacharya; Amitabha De

Abstract FeCl 3 -doped polypyrrole samples have been synthesized at different temperatures, at 308 K and below. The induced defects in the doped structure were analyzed by positron lifetime and Doppler broadening of the annihilation radiation. The magnitude of the conductivity measured in the samples was found to increase monotonically with the induced defect concentration.


Chemical Physics | 2003

Self association of sodium salicylate system

Subir Kumar Das; Shrabani Das; B. Nandi Ganguly; Amarnath Maitra

Abstract The aggregation behavior of sodium salicylate (SS) in aqueous solutions has been studied by positronium annihilation technique. From the change of the pick-off life time as well as the intensity of the ortho -positronium component, it has been concluded that the minimal hydrotropic concentration (MHC) of SS lies in the range 0.9–1.0 M concentration. To support the above contention, the molecular association of SS has also been investigated by the changes in light scattering intensity, conductivity as well as NMR data. These experiments conjointly infer that the stacking of SS molecules appears to start beyond 0.9 M concentration.


International Journal of Radiation Applications and Instrumentation. Part A. Applied Radiation and Isotopes | 1987

Study of aggregation behaviour in HDEHP—n-heptane system by positron annihilation technique

B. Nandi Ganguly; P. Sen

The aggregation behaviour of di(2-ethyl hexyl) phosphoric acid (HDEHP) in n-heptane was studied by the positron annihilation technique. The discontinuity in the positronium formation intensity, I2, as a function of HDEHP concentration suggested formation of close aggregates of HDEHP molecules.


Radiation Physics and Chemistry | 1997

Positronium reactions in the triton X-100-p-nitro phenol system

Subir Kumar Das; B. Nandi Ganguly

Abstract The positronium reactions have been used as a probe to study the solubilization of p-nitro phenol within the micellar phase of a Triton X-100 solution and the corresponding changes in the molecular association phenomenon. The presence of p-nitro phenol resulted in an enhancement of micellization which has been corroborated by surface tension measurements. This paper also lays emphasis on the secondary aggregation phenomenon of Triton X-100 molecules at the far post-micellar stage (≈10–15 mM). The solubilization of p-nitro phenol at various stages of aggregation has been discussed through the interaction with positronium atoms by setting up a kinetic model and reaction equilibria.


Colloids and Surfaces A: Physicochemical and Engineering Aspects | 2000

Guest molecules in Triton X-100 microemulsion: studied by positron annihilation technique and absorption spectroscopy

Subir Kumar Das; B. Nandi Ganguly

Abstract Positron annihilation lifetime measurements have been performed in water in oil (w/o) microemulsion (ME) of Triton X-100/butanol, n -heptane system in the presence of additives, UO +2 2 and p -nitro phenol (PNP). The microenvironment of the guest molecules in the ME phase was studied by the positronium (Ps) reaction-rate constant. The Ps reaction rate constant values with UO +2 2 in ME changed gradually as a function of water content in ME phase where as a considerable enhancement of Ps reaction rate constants with PNP was observed in the same phase. Furthermore, the solubilization of the probe molecules in the different microphase of the ME system was investigated through the UV-VIS absorption spectra. The results show that UO +2 2 ions were preferentially occupied in the polar water pool of ME but PNP molecules were distributed in the interfacial region (intermediate polarity) of the ME phase.


Polymer | 1998

Positron annihilation study on γ-irradiated cellulose acetate matrix

V. S. Subrahmanyam; Subir Kumar Das; B. Nandi Ganguly; A. Bhattacharya; Amitabha De

Abstract A cellulose acetate matrix was irradiated in the dose range 0–250 kGy by y radiation from a 60 Co source under an argon atmosphere; positron lifetime experiments were performed under the same atmosphere at room temperature. The results reveal a dominant intermediate component τ 2 (∼430 ps) attributable to a crystalline macrocellulosic domain. Important changes are shown by the long-lived pick-off component τ 3 due to the degradation in the polymer matrix.


Journal of Radioanalytical and Nuclear Chemistry | 1994

Interaction of positronium with Co2+ and Cu2+ ions in aqueous solutions

B. Nandi Ganguly; V. S. Subrahmanyam; P.K. Sarkar

Interactions of positronium in aqueous solutions of Co2+ and Cu2+ ions have been investigated at room temperature (297 K) at varying concentrations using both lifetime and Doppler broadening of annihilation radiation techniques. In the case of Co2+, the results indicate spin conversion reaction alone. However, in the case of Cu2+, oxidation is predominant with a small contribution of spin conversion reaction. The corresponding rate constants have been evaluated.


Journal of Colloid and Interface Science | 1997

Reverse Micelle Formation of Triton X-100 in Butanol andn-Heptane Mixed Solvents Studied by the Positron Annihilation Technique

Subir Kumar Das; B. Nandi Ganguly

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Subir Kumar Das

Saha Institute of Nuclear Physics

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V. S. Subrahmanyam

Saha Institute of Nuclear Physics

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A. Bhattacharya

Saha Institute of Nuclear Physics

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Amitabha De

Saha Institute of Nuclear Physics

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P.K. Sarkar

Variable Energy Cyclotron Centre

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D. Banerjee

University of Calcutta

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D. Sanyal

University of Calcutta

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P. Sen

Saha Institute of Nuclear Physics

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Pranab K. Sarkar

Variable Energy Cyclotron Centre

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