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Temperature dependence of the damping constant and the order parameter close to the lambda phase transitions in ammonium halides
Date
2006-10-01
Author
Yurtseven, Hasan Hamit
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This study gives our calculation for the damping constant, using the expressions derived for an Ising pseudospin-phonon coupled system in the ammonium halides (NH4Cl and NH4Br). For this calculation of the damping constant, we use the temperature dependence of the order parameter calculated from the molecular field theory. We predict here the damping constants for the v(5) (174 cm(-1)) and v(5) (177 cm(-1)) Raman modes of NH4Cl and NH4Br, respectively, below T-lambda and compare them with our observed bandwidths measured as a function of temperature for those phonon modes at zero pressure.
Subject Keywords
Instrumentation
,
Analytical Chemistry
,
Spectroscopy
,
Atomic and Molecular Physics, and Optics
URI
https://hdl.handle.net/11511/36136
Journal
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
DOI
https://doi.org/10.1016/j.saa.2005.10.054
Collections
Department of Physics, Article
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Bandwidths studied as a function of temperature in ammonium halides near T-lambda
Yurtseven, Hasan Hamit (Elsevier BV, 2005-12-01)
This study gives our analysis of the Raman bandwidths using the soft mode-hard mode coupling model applied to ammonium halides. The temperature dependence of our observed bandwidths for the nu(5)(174 cm(-1)) Raman mode of NH4Cl and nu(5)(177 cm(-1)) Raman mode of NH4Br, is analyzed close to phase transitions. From our analysis, we obtain beta = 0.13 as the values of the critical exponent for the order parameter in the first order phase region for the ammonium halides.
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H. H. Yurtseven, “Temperature dependence of the damping constant and the order parameter close to the lambda phase transitions in ammonium halides,”
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
, pp. 421–427, 2006, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/36136.