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This monograph is a compilation of the incremental reports on the research work which was presented in several scientific events. The contributions to as many as 23 scientific events starting from the year 2006 have been put together in this volume. The research work is essentially a consequence of the experimental finding from the difficult task of HR PMR Studies in Solids, on single crystalline specimen. The determination of the Shielding tensor of organic molecule on interpretation indicated that the contribution to Shielding tensor of a proton at a lattice site has three contributions to sum up. First is the intra-molecular contribution obtainable by QM calculations, second is from the molecules in the neighborhood within the range of 100 Angstrom radius spherical volume element which can be calculated by discrete summation, and the third is the remaining macroscopic continuum bulk susceptibility which is also specimen shape dependent. All these had basically to revisit the criteria for the validity of point-dipole-approximation. The basic characteristic of the approximation is that the validity criterion is a matter of relative distances more than the absolute magnitudes.

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Aravamudhan, Sankarampadi
Dr.S.Aravamudhan joined regular service as teaching faculty in the year 1985 at the Department of Chemistry, North Eastern Hill University, Shillong, Meghalaya, India. On 30th November 2006 attained the age of superannuation and has been active in research as Emeritus Professor. Research interests are: Magnetic Resonance and Quantum Chemistry.

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