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Vibrational study on phase transition in ammonium Rochelle salt
Author(s) -
Kanesaka Isao,
Kita Hayato
Publication year - 1992
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250231102
Subject(s) - raman spectroscopy , chemistry , deuterium , phase transition , salt (chemistry) , molecule , infrared spectroscopy , ammonium , crystallography , phase (matter) , infrared , ion , chemical physics , thermodynamics , organic chemistry , optics , physics , quantum mechanics
Polarized Raman spectra of partially deuterated ammonium Rochelle salt in the region of O—D stretchings were observed at room temperature. The O—D stretchings were assigned by reference to intensity variations in polarized spectra. The O—D stretchings and also the decoupled N—D stretchings in the infrared spectrum split into many bands below T c . Some bands split abruptly and others gradually. The abrupt splitting is ascribed to a displacive structural change of water molecules in relation to tartrate ions which accompanies ordering at one of two NX 4 + sites (X = H or D). The gradual splitting is ascribed to gradual freezing of reorientational motions at the other NX 4 + site. The mechanism of the phase transition is discussed in terms of these structural changes.