硝酸胺晶体中硝酸根的u_1全对称振动模的临界拉曼强度行为及其热力学解释

硝酸胺晶体中硝酸根的ｕ＿１全对称振动模的临界拉曼强度行为及其热力学解释丁贤德，吴国初（中科院化学所北京１０００８０）ＴｈｅＣｒｉｔｉｃａｌＲａｍａｎＩｎｔｅｎｓｉｔｙＢｅｈａｖｉｏｒｏｆｔｈｅＮｉｔｒａｔｅｕ＿１ＭｏｄｅａｎｄＩ０ｓＴｈｅｒｍｏｄｙｎ...

The Critical Raman Intensity Behavior of the Nitrate u_1 Mode and I0s Thermodynamic Interpretation for The Phase Transitions of Crystalline NH_4NO_3

Abstract The phase transitions of crystalline NH_4NO_3 are studied through the analysis of the variation of the Raman intensities I_R of the nitrate u_1 mode in the critical regions， Critical exponentpcan be elucidated through the fitting of I_R with |T-T_c|~B.It is demonstrated thatpis related to the thermodynamic quan-tities of the phase transitions. The analysis after an expol1ential model is ex-plored with results rather suggestive. Another parameter， the ratio of the pre-exponential factors in the exponential model which can only be elucidated throufgh both the spectroscopic and thermodynamic quantities for the low and high temperature phases is also introduced． It is demonstrated that this param-eter could bear much important information of the phase transitions as far as the degree of the structural order of the critical regions is concerned.