Yurtseven H, Kayişoğlu D
Department of Physics, Istanbul Technical University, Maslak, Turkey.
Spectrochim Acta A Mol Biomol Spectrosc. 2002 Jun;58(8):1823-30. doi: 10.1016/s1386-1425(01)00632-1.
This study gives our analysis of the disorder-induced Raman modes of v7 (93 cm(-1)) and v5 (144 cm(-1)) close to the lambda-phase transition (P = 0) in the NH4Cl crystal. We describe the critical behavior of the frequency shifts for those modes by a power-law formula and using our Raman data we obtain the value of 0.1 for the critical exponent which can also describe the critical behavior of the thermal expansivity and the specific heat of NH4Cl close to its lambda-phase transition (Tlambda = 242.9 K).
本研究给出了我们对NH₄Cl晶体中接近λ相变(P = 0)时v7(93 cm⁻¹)和v5(144 cm⁻¹)的无序诱导拉曼模式的分析。我们用幂律公式描述了这些模式频移的临界行为,并利用我们的拉曼数据得到了临界指数的值为0.1,该指数也能描述NH₄Cl接近其λ相变(Tλ = 242.9 K)时热膨胀系数和比热容的临界行为。