The Pippard relations have been reformulated in terms of the spectroscopic parameters and applied to the NH4Cl system in the vicinity of its lambda-transition. We have effectively tested some of these relations in an earlier study where we have used, for the frequency shift, data for the nu5 lattice mode of NH4Cl. Here, using our observed frequency shifts for the internal mode, nu2 of NH4+, we have obtained a good fit to the Pippard relations for temperatures below T(lambda) for the NH4Cl system. We have then been able to extract the frequency shift data for the nu2 internal mode as a function of temperature, using the specific heat and also thermal expansion data from the literature. The method of analysis for obtaining the thermodynamic data from the spectroscopically measured quantities or vice versa is given here.


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The effect of an imposed magnetic field on the thermal convection between rigid plates heated from below under the influence of gravity is numerically simulated in a computational domain with periodic horizontal extent. The numerical technique is based on solenoidal basis functions satisfying the boundary conditions for both velocity and induced magnetic field. The expansion bases for the thermal field are also constructed to satisfy the boundary conditions. The governing partial differential equations are ...
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Citation Formats
H. H. Yurtseven, “SPECTROSCOPIC MODIFICATIONS OF PIPPARD RELATIONS AND THEIR APPLICATION TO NH4CL,” JOURNAL OF MOLECULAR STRUCTURE, pp. 243–246, 1994, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/56157.