A Raman signature of the incommensurate-commensurate phase transition (lock-in) in a crystalline monomer diacetylene : pTS
Open Access
- 1 January 1982
- journal article
- Published by EDP Sciences in Journal de Physique
- Vol. 43 (5), 755-759
- https://doi.org/10.1051/jphys:01982004305075500
Abstract
The low frequency polarized Raman spectra of monomer pTS crystals have been studied as a function of temperature. We observe two features associated with the incommensurate phase, which exists between Ti ~ 200 K and T1 ~ 155 K, and the related phase transitions. A soft mode (ampliton) is detected at all temperatures below Ti - 15 K and corresponds to a displacive behaviour in this temperature range. A line at 13 cm-1 is present only in the incommensurate phase. A possible mechanism for the detection of that line in this sole phase is discussed and shown to be in complete agreement with the neutron and I.R. dataKeywords
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