Incommensurate-Commensurate Phase Transition of Intramolecular Hydrogen-Bonded System : 5-Bromo-9-Deuteroxyphenalenone (d-BrHPLN)

概要

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Low-temperature X-ray Weissenberg photographs of deuterated 5-bromo-9-hydroxyphenalenone (d-BrHPLN) were taken at 14.4 K to investigate the phase transition of an intramolecular and isolated hydrogen-bonded system composed of a tautomeric molecule. The system has one hydrogen bond in a rigid molecular skeleton, with the hydrogen atom being replaced by deuterium. The superlattice reflection is found at (h k+0. 5 0) at 14.4 K, and it starts to deviate from the commensurate position above T_c=22.8 K on heating. The transition is of the first kind and is characterized by a commensurate-incommensurate transition. The peak shift defined as 0.5+δ was also measured. Above T_I=34.5 K, the profile becomes very broad and shows diffuse scattering behavior. The transition is of the second kind and is characterized by a so-called incommensurate-normal phase transition.
社団法人日本物理学会の論文
1994-12-15