Raman frequency shifts of an internal mode near the tricritical and second order phase transitions in NH4Cl

---

Atıf İçin Kopyala

Yurtseven H., Tumkaya M.

SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY, cilt.62, ss.926-930, 2005 (SCI-Expanded)

• Yayın Türü: Makale / Tam Makale
• Cilt numarası: 62
• Basım Tarihi: 2005
• Doi Numarası: 10.1016/j.saa.2005.01.031
• Dergi Adı: SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
• Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
• Sayfa Sayıları: ss.926-930
• Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

This study gives our analysis for the frequency shifts of the nu(2)(1708 cm(-1)) Raman mode in NH4Cl close to its tricritical (P = 1.6 kbar) and second order (P = 2.8 kbar) phase transitions. From our analysis, we extract the values of the critical exponent which describes the critical behavior of the Raman frequency shifts for this internal mode for the pressure conditions studied in NH4Cl. Our exponent value of alpha approximate to 0.2 for the tricritical phase transition is close to the values of 1/16 (T < T-c) and 1/8 (T > T-c) for the specific heat, predicted from a 3D Ising model. Our exponent values for the second order phase transition (P = 2.8 kbar) for T < T-c and T > T-c are comparable with those reported in earlier studies. (c) 2005 Elsevier B.V. All rights reserved.