Relaxation process and phase transition of lanthanide liquid crystalline complexes by photoacoustic spectroscopy  

作　　者：李俊嘉 杨跃涛 刘晓峻 张淑仪 张仲宁 

机构地区：[1]Key Laboratory of Modern Acoustics, Ministry of Education, Institute of Acoustics, Nanjing University

出　　处：《Journal of Rare Earths》2008年第3期320-325,共6页稀土学报（英文版）

基　　金：the National Natural Science Foundation of China (10574073, 10574071)

摘　　要：Lanthanide-containing liquid crystals exhibiting smectic A phase close to room temperature were obtained. Photoacoustic （PA） spectroscopy was used to study the spectral properties and phase transitions of liquid crystalline metal complexes. It was found that PA intensity of the ligand had a relationship with the probability of nonradiative transitions, which increased in the order of Eu（tta）3L2〈La（tta）3L2〈 Tb（tta）3L2〈Er（tta）3L2. The relaxation processes of the complexes were studied in depth from two aspects： radiative and non-radiative processes, combining with their fluorescence spectra. Phase transitions of europium（m） and erbium（m） complexes, in the temperature range of 383-358 K, could be clearly monitored by both PA amplitude and PA phase signals. As the temperature crossed the transition point, PA amplitude showed a minimum and PA phase a maximum. The results indicated that PA technique could serve as a new tool for investigating the physicochemical properties of liquid crystals containing metal ions.Lanthanide-containing liquid crystals exhibiting smectic A phase close to room temperature were obtained. Photoacoustic （PA） spectroscopy was used to study the spectral properties and phase transitions of liquid crystalline metal complexes. It was found that PA intensity of the ligand had a relationship with the probability of nonradiative transitions, which increased in the order of Eu（tta）3L2〈La（tta）3L2〈 Tb（tta）3L2〈Er（tta）3L2. The relaxation processes of the complexes were studied in depth from two aspects： radiative and non-radiative processes, combining with their fluorescence spectra. Phase transitions of europium（m） and erbium（m） complexes, in the temperature range of 383-358 K, could be clearly monitored by both PA amplitude and PA phase signals. As the temperature crossed the transition point, PA amplitude showed a minimum and PA phase a maximum. The results indicated that PA technique could serve as a new tool for investigating the physicochemical properties of liquid crystals containing metal ions.

关 键 词：photoacoustic spectroscopy lanthanide complex liquid crystal phase transition rare earths 

分 类 号：TB302[一般工业技术—材料科学与工程]