Wide-angle polarization analysis on the multi-axis crystal spectrometer for the study of collective and single particle dynamics of methanol at its prepeak

Neutron polarization analysis capability with a large scattering angle and momentum transfer coverage has not been widely implemented for the separation of coherent and incoherent quasi-elastic neutron scattering (QENS) spectra. A feasibility test for soft condensed matter applications was performed...

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Bibliographic Details
Published inPhysica. B, Condensed matter Vol. 564; pp. 166 - 171
Main Authors Chen, Wangchun, Watson, Shannon, Qiu, Yiming, Rodriguez-Rivera, Jose A., Faraone, Antonio
Format Journal Article
LanguageEnglish
Published Amsterdam Elsevier B.V 01.07.2019
Elsevier BV
Subjects
Coherent scattering
Collective dynamics
Condensed matter physics
Data analysis
Deuteration
Elastic scattering
Incoherent scattering
MACS
Methanol
Momentum transfer
Multiaxis
Neutron flux
Neutron scattering
Neutrons
Polarization
Position measurement
QENS
Scattering
Scattering angle
Single particle dynamics
Spectrum analysis
Spin incoherent scattering
Wide angle polarization analysis
Collective dynamics
MACS
Wide angle polarization analysis
Spin incoherent scattering
Single particle dynamics
QENS
Coherent scattering
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Summary:Neutron polarization analysis capability with a large scattering angle and momentum transfer coverage has not been widely implemented for the separation of coherent and incoherent quasi-elastic neutron scattering (QENS) spectra. A feasibility test for soft condensed matter applications was performed on the Multi-Axis Crystal Spectrometer (MACS) at the NIST Center for Neutron Research (NCNR). This capability benefitted from the high flux wide angle polarization analysis capability recently developed on MACS for hard condensed matter investigations. The experimental procedure is thoroughly described on how to take data and perform polarization efficiency correction before further data analysis is done. This capability was employed to unambiguously separate the coherent and incoherent signal from the QENS spectra for the investigation of both the collective and the single particle dynamics in partially deuterated (CH3OD, D 99.5% purity) methanol. By studying a Q range encompassing the prepeak position, it was possible to directly measure the dynamics of the h-bonding associates which originate the prepeak signal, without contamination from the incoherent scattering, in spite of the relative weakness of the coherent scattering.
ISSN:0921-4526
1873-2135
DOI:10.1016/j.physb.2018.11.060