THE CRITICAL-BEHAVIOR OF THE RAMAN INTENSITIES OF THE LATTICE MODES IN AMMONIUM HALIDES


YURTSEVEN H., SHERMAN W.

JOURNAL OF MOLECULAR STRUCTURE, vol.294, pp.175-178, 1993 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 294
  • Publication Date: 1993
  • Doi Number: 10.1016/0022-2860(93)80343-t
  • Title of Journal : JOURNAL OF MOLECULAR STRUCTURE
  • Page Numbers: pp.175-178

Abstract

Our observed Raman intensities for the lattice modes of TA(M)(93 cm-1) and TO(M)(144cm-1) of NH4Cl were used to extract the critical exponents for the order parameter in this crystal system. Our exponent values are 0.15+/-0.02 (1st order, T(c)=241 K, P=0), 0.24+/-0.04 (tricritical, T(c)=255 K, P=1.5 kbar) and 0.33+/-0.10 (2nd order, T(c)=268 K, P=3 kbar), which agree with the model predictions.