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          Institute: MPI für medizinische Forschung     Collection: Abteilung Biophysik     Display Documents

ID: 23278.0, MPI für medizinische Forschung / Abteilung Biophysik
o-Terphenyl: flips of the end rings in the crystal phase
Translation of Title:o-Terphenyl: flips of the end rings in the crystal phase
Authors:Stumber, Michael; Zimmermann, Herbert; Schmitt, Heike; Haeberlen, Ulrich
Date of Publication (YYYY-MM-DD):2001-07-10
Title of Journal:Molecular Physics
Journal Abbrev.:Mol. Phys.
Issue / Number:13
Start Page:1091
End Page:1098
Review Status:Peer-review
Audience:Experts Only
Intended Educational Use:No
Abstract / Description:We demonstrate by selective saturation deuteron NMR experiments on a crystal of selectively deuterated o-terphenyl (OTP) that both end rings I and II attached to the central ring undergo thermally activated flip motions. In crystals of OTP, the end rings I and II are not symmetry related, their dynamics can be different and, in fact, is different, although mutual steric hindrance of the rings suggests a strong correlation. We measured the rates kI and kII of the flips of both end rings I and II as a function of temperature. We find that, independent of the temperature, kI exceeds kII by roughly a factor of 100. This result excludes correlated flips of rings I and II in the sense that a flip of one ring necessarily entails a flip of the other. The activation energies EaI and EaII of the two flip processes turn out to be equal (80.5 kJ mol-1) within experimental errors. This is taken as a hint that the flips are, after all, related to each other. A mechanism is proposed of how this is possible under the constraint kI>kII
External Publication Status:published
Document Type:Article
Communicated by:Wulf Kaiser
Affiliations:MPI für medizinische Forschung/Abteilung Biophysik/
MPI für medizinische Forschung/Abteilung Molekulare Neurobiologie/
MPI für medizinische Forschung/Forschungsgruppe Molekülkristalle/
Identifiers:URI:http://taylorandfrancis.metapress.com/app/home/con... [Abstract]
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