A K Singh
Articles written in Pramana – Journal of Physics
Volume 64 Issue 1 January 2005 pp 135-139
A modified Flory theory along with the Auerbach and Altenberg relations has been employed for the computation of ultrasonic velocity of three quaternary liquid mixtures and a comparative study of all the three relations has then been carried out.
Volume 64 Issue 2 February 2005 pp 299-304
Lattice vibrational properties of transition metal carbides (TiC, ZrC and HfC) have been presented by including the effects of free-carrier doping and three-body interactions in the rigid shell model. The short-range overlap repulsion is operative up to the second neighbour ions. An excellent agreement has been obtained between theory and experiment for their phonon dispersion curves and Debye temperature variations. It is concluded that the contributions of free-carrier doping and three-body interactions are essential for the description of the lattice dynamics of these carbides.
Volume 65 Issue 6 December 2005 pp 1109-1114
A new type of discrete VLF emissions recorded at the low-latitude ground station Varanasi (geomag. lat. 14°55′ N, geomag. long. 154°E;
Volume 82 Issue 2 February 2014 pp 409-412 Contributed Papers
In the present work, results of upconversion emission in various powder samples have been discussed. The powder upconversion phosphors such as La2O3:Er3+/Yb3+, LaF3:Er3+/Yb3+, CeO2 :Er3+/Yb3+, CeF3:Er3+/Yb3+ were prepared and their upconversion emission, using 976 nm wavelength excitation, was investigated in depth. These phosphors have shown good upconversion emission in the visible region except for the CeF3:Er3+/Yb3+ phosphor. Two intense bands around 525 and 550 nm due to the 2H11/2$\to$4I15/2 and 4S3/2 $\to$ 4I15/2 transitions, respectively, are found to be in a thermally coupled state in these samples. The intensity ratio of these two bands permitted us to estimate the temperature of the environment. The pump power studies of the emission bands of these samples are also made to understand the dynamics of the upconversion emission.
Volume 82 Issue 2 February 2014 pp 445-449 Contributed Papers
AMichelson interferometer-based technique has been used to measure the deformation of dielectric-coated mirror, caused by an incident repetitive pulsed laser beam with high average power. Minimum measurable deformation of 17 nm is reported.
Volume 82 Issue 6 June 2014 pp 1119-1119 Erratum
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