Low temperature methyl group tunneling in polynorbornenes - Prove of missing spin conversation
The methyl group tunneling in amorphous materials is still not completely understood although some investigations are present in the literature. Especially no investigations at cryogenic temperatures are known. Therefore, it is suggested to carry out neutron backscattering on IN16B with the BATS option at cryogenic temperatures on a polynorbornene. In previous experiment on IN16B/BATS (6-04-285) an anomalous broadening of the low temperature resolution measured at a cryostat temperature of 40 mK in comparison to a corresponding polynorbornene was observed. As the cryostat temperature was 40 mK the temperature estimated from the neutron scattering data by the principle of detailed balance was around 1 K. This temperature difference could be explained by a missing spin conversion, a possibility hypothesized in literature. As the sample was wrapped in an Al foil an adverse effect of aluminum could not be ruled out completely. Therefore, it is suggested to repeat the measurement without wrapping the sample in Al. The data will be analyzed by the rotational rate distribution model for methyl group rotation extended by the scattering function for quantum tunneling.
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The recommended format for citing this dataset in a research publication is in the following format:
SCHOENHALS Andreas; APPEL Markus; Bernhard Frick; SZYMONIAK Paulina Elzbieta and ZORN Reiner. (2023). Low temperature methyl group tunneling in polynorbornenes - Prove of missing spin conversation. Institut Laue-Langevin (ILL) doi:10.5291/ILL-DATA.6-04-288
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