title: Pippard relations applied to the lambda-phase transition in NH4Br.
abstract: We establish here a linear variation of the specific heat C(P) with the frequency shifts (1/nu)(partial differential nu/partial differential T)P close to the lambda-phase transition in NH4Br (Tlambda = 234 K). This linear relationship is based on our spectroscopically modified Pippard relations. For this verification of our relations, we use our observed Raman frequencies of the lattice mode of nu7 (56 cm(-1)) and the internal mode of nu2 (1684 cm(-1)) in the NH4Br crystalline system. Our study given here indicates that the thermodynamic data can be obtained from the measured frequencies.
authors.affiliation: Department of Physics, Middle East Technical University, 06531 Ankara, Turkey. hamit@metu.edu.tr
authors.forename: H
authors.initials: H
authors.lastname: Yurtseven
authors.forename: A
authors.initials: A
authors.lastname: Yanik
authors.forename: S
authors.initials: S
authors.lastname: Sen
mesh_terms: D001965:Bromides / Q000737:chemistry*; D002627:Chemistry, Physical / Q000379:methods*; D003460:Crystallization; D006358:Hot Temperature; D044367:Phase Transition; D011312:Pressure; D000644:Quaternary Ammonium Compounds / Q000737:chemistry*; D013053:Spectrophotometry / Q000379:methods*; D013059:Spectrum Analysis, Raman / Q000379:methods; D013696:Temperature; D013816:Thermodynamics; D044366:Transition Temperature
chemical_list: D001965:Bromides; D000644:Quaternary Ammonium Compounds; C051470:ammonium bromide