Analysis of the frequency shifts close to the second order phase transition in NH4Cl


Yurtseven H., Kayisoglu D.

SPECTROSCOPY LETTERS, cilt.34, ss.147-157, 2001 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 34 Konu: 2
  • Basım Tarihi: 2001
  • Doi Numarası: 10.1081/sl-100002004
  • Dergi Adı: SPECTROSCOPY LETTERS
  • Sayfa Sayıları: ss.147-157

Özet

In this study we analyzed observed Raman data for the frequencies of the disorder-induced modes of v(7) (93 cm(-1)) and vs (144 cm(-1)) in the second order phase region of NH4Cl (P = 2.8 kbar). By means of a power-law formula describing the critical behaviour of the frequency shifts 1/v(partial derivativev/partial derivativeT)p for those phonon modes studied, we extract the critical exponent value of a = 0.25, which can also describe the critical behaviour of the specific hear Cp close to the second order phase transition in NH4Cl. Within this content, our spectroscopically modified Pippard relations are introduced here.