Soft phonon and central peak scattering in a molecular crystal system: C6Cl4O2 (chloranil)

• W. D. Ellenson

  Research Establishment Riso/, DK−4000 Roskilde, Denmark

• J. K. Kjems

  Research Establishment Riso/, DK−4000 Roskilde, Denmark

抄録

Elastic and inelastic neutron scattering has been used to study the continuous structural transition in chloranil at Tc=90.3 K. The transition results in a doubling of the monoclinic unit cell along the c axis and the molecular displacements correspond to a staggered rotation, φ, about axes perpendicular to the molecular planes. The temperature dependence of the order parameter, φ, has been determined from superlattice Bragg intensities with the result φ∝ (Tc−T)0.33±0.02 for 0.005< (1−T/Tc) <0.5. The response from the zone boundary phonon, whose eigenvector corresponds to the distortions below Tc, shows a pronounced softening in the temperature range 100–300 K. At temperatures below 140 K the spectrum also contains a central component diverging at Tc which is resolution limited in energy, but shows considerable width and anisotropy in momentum space.

収録刊行物

• The Journal of Chemical Physics

  The Journal of Chemical Physics 67 (8), 3619-3623, 1977-10-15

  AIP Publishing

キーワード

• Physical and Theoretical Chemistry
• General Physics and Astronomy

詳細情報

• CRID: 1363107369024122880
• NII論文ID: 30015671815
• DOI: 10.1063/1.435298
• ISSN: 10897690
• ISSN: 00219606
• Web Site: https://pubs.aip.org/aip/jcp/article-pdf/67/8/3619/18908258/3619_1_online.pdf
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