Quasielastic and inelastic neutron scattering study of methyl group rotation in solid and liquid pentafluoroanisole and pentafluorotoluene

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Details zur Publikation

Autorinnen und Autoren: Smuda C, Gemmecker G, Unruh T
Zeitschrift: Journal of Chemical Physics
Verlag: AMER INST PHYSICS
Jahr der Veröffentlichung: 2008
Band: 128
Heftnummer: 19
ISSN: 0021-9606


Abstract


The rotational motion of the methyl group in pentafluoroanisole (PFA) and in pentafluorotoluene (PFT), respectively, was investigated by quasielastic neutron scattering (QENS). For solid PFA, the rotation can be described by a model for uniaxial rotational jumps between three equidistant sites on a circle. Similar to the molecular structure of alpha-toluene, two nonequivalent methyl groups in the unit cell with two different rotational barriers were found for solid PFT. From the analysis of the quasielastic scattering, the activation energies were determined. The barrier heights could be evaluated from bands in the inelastic part of the spectra. The methyl group dynamics in the liquid state is evaluated for both substances using different scattering functions, which are discussed. An empirical model for the description of the contribution of methyl groups in liquids of small organic molecules to the QENS spectra is presented. It is demonstrated that the process of methyl group rotation in the liquid phase is nearly free of a barrier. (c) 2008 American Institute of Physics.



FAU-Autorinnen und Autoren / FAU-Herausgeberinnen und Herausgeber

Unruh, Tobias Prof. Dr.
Professur für Nanomaterialcharakterisierung (Streumethoden)


Einrichtungen weiterer Autorinnen und Autoren

Technische Universität München (TUM)


Zitierweisen

APA:
Smuda, C., Gemmecker, G., & Unruh, T. (2008). Quasielastic and inelastic neutron scattering study of methyl group rotation in solid and liquid pentafluoroanisole and pentafluorotoluene. Journal of Chemical Physics, 128(19). https://dx.doi.org/10.1063/1.2894847

MLA:
Smuda, Christoph, Gerd Gemmecker, and Tobias Unruh. "Quasielastic and inelastic neutron scattering study of methyl group rotation in solid and liquid pentafluoroanisole and pentafluorotoluene." Journal of Chemical Physics 128.19 (2008).

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