首页 | 本学科首页   官方微博 | 高级检索  
     


Raman spectroscopic investigations of the structure and phase transitions of liquid crystalline lead(II) alkanoates
Authors:J. Schwede   L. K  hler  H. P. Groß  mann  M. Pietralla  H. D. Burrows
Affiliation:J. Schwede ,L. Kö,hler,H. P. Groß,mann,M. Pietralla,H. D. Burrows
Abstract:Lead(II) alkanoates with even chain lengths from octanoate to octadecanoate have been investigated by Raman spectroscopy. In the low frequency region, transverse and longitudinal acoustical modes (TAM, LAM) have been assigned. It was shown that LAM-1 is the vibration of the double chain with the node of the vibration in the Pb2+ layer. A fully extended conformation of the chains in the low temperature phase was confirmed. The frequencies and intensities of the LAMs as compared with those of the alkanes and the fatty acids led to an estimate of the force constant and polarizability of the Pb2+ -COO- bond relative to the C-C bond. The defects at the chain ends were investigated in the ρ(CH3) and v(CC) region. For the intermediate (CM) phase, both the Pb2+ layer distance reduction and the chain length independent enthalpy contributions can be attributed mainly to defects at the chain ends.
Keywords:
本文献已被 InformaWorld 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号