氯化癸铵的低频拉曼光谱研究

STUDY ON LOW-FREQUENCY RAMAN SPECTRA OF n-DECYLAMMONIUM CHLORIDE

在290—340K的温度范围内考察了氯化癸铵的低频拉曼光谱,指认了210cm^(-1)附近的谱带为分子烷基链的纵向声子振动带,低于100cm^(-1)的谱带为晶格振动带,结果表明DeAC晶体存在313K和321K两个结构相变。在313K以下的低温相,DeAC分子以完全有序的全反式链构象存在,在313—321K的中间相,分子烷基链出现了旁式构象,高温相与中间相相比主要是分子链横向堆积有序度明显降低,而分子链构象特征无明显差异。

The low-frequency Raman spectrum of n-decylammonium chloride was measuredas a function of temperature in the temperature range from 290 to 340K, and thelongitudinal acoustical mode vibration band was assigned. The results showed thatthere are two phase transitions at 313K and 321K, respectively. The phase transitionat 313K is mainly induced by change of hydrocarbon chain conformations, while thatat 321K is mainly induced by change of order degree of molecular packing. Theresults suggest low-frequency Raman spectroscopy is a useful probe of structuralphase transition for long-chain compounds.