Department of Physics
Permanent URI for this collectionhttp://localhost:4000/handle/123456789/1932
Browse
4 results
Search Results
Item A study of the effect of annealing temperatures and time periods on the hyperfine field distributions of Fe79B16Si5 metallic glass near and below the crystallization temperature was carried out using 57Fe Mössbauer spectroscopy. The effect of crystallization during annealing as a function of annealing time on the average hyperfine magnetic field, , and the relative change of the probability of hyperfine fields, P(H), with respect to that of the as-received sample are also discussed.(Springer, 1999-11) Bandyopadhyay, DebashisThis paper reports 57Fe Mössbauer spectroscopic studies of the polycrystalline samples of the substitutionally disordered, isostructural (fcc), ternary alloy system Fe80-xNixCr20 for x = 30, 26, 19 and 14 in the temperature range of 10–295 K. The data have been analyzed in terms of the magnetic phase transitions occurring in these alloys by examining the temperature dependence of the various Mössbauer parameters like line‐width, center shift, resonance area, distribution of hyperfine field, P(H), and the average hyperfine field 〈H〉. An estimate of the magnetic transition temperature T C is made for the alloys with x = 30 and 26 and these results are compared with those previously obtained by magnetic measurements and neutron diffraction experiments. The data for the second order Doppler shift have been analyzed to estimate the Debye temperature ΘD for alloys with x = 30 and 26.Item Purpose-led Publishing logo. Study of hyperfine-field distributions and the lattice dynamics of Fe50Ni30Cr20 alloy by using 57Fe Mössbauer spectroscopy(IOP, 1999) Bandyopadhyay, DebashisThis paper reports a 57Fe Mössbauer spectroscopic study of a polycrystalline sample of the substitutionally disordered, isostructural (fcc), ternary alloy Fe50Ni30Cr20 over the temperature range 10 to 295 K. The data have been analysed in terms of the magnetic phase transitions occurring in the alloy by examining the temperature dependence of the Mössbauer parameters. The Curie temperature has been determined by fitting the average hyperfine-field values obtained at different temperatures. In order to achieve a detailed understanding of the nature of the hyperfine-field distribution corresponding to the Mössbauer spectra of this alloy, the curves representing the probabilities of the hyperfine-field distributions versus the hyperfine field have been refitted by using two independent Gaussians. On the basis of these fits, the local magnetic ordering of this alloy at low temperature has been described. The data on the second-order Doppler shift have been analysed in order to obtain an estimate of the Debye temperature, ΘD, and a description of the lattice dynamics.Item Time resolved fluorescence spectroscopy of quinine sulphate, quinidine and 6-methoxyquinoline: pH dependence(Elsevier, 1992-03) Pant, Debi D.The excited state dynamics of quinine sulphate (QS), quinidine (Qd) and 6-methoxyquinoline (6MQ) has been studied as a function of pH in steady state and nanosecond time resolved fluorescence experiments. The solvent relaxation process is a dominant process for all the molecules studied, irrespective of pH. Moreover, 6MQ undergoes a proton transfer reaction in the excited state at pH 7 whereas QS and Qd do not exhibit excited state protonation.Item Time resolved fluorescence spectroscopy of quinine sulphate, quinidine and 6-methoxyquinoline: pH dependence(Elsevier, 1992-03) Pant, Debi D.The excited state dynamics of quinine sulphate (QS), quinidine (Qd) and 6-methoxyquinoline (6MQ) has been studied as a function of pH in steady state and nanosecond time resolved fluorescence experiments. The solvent relaxation process is a dominant process for all the molecules studied, irrespective of pH. Moreover, 6MQ undergoes a proton transfer reaction in the excited state at pH 7 whereas QS and Qd do not exhibit excited state protonation.