We have built a sample holder (called a center stick or sample stick) for performing simultaneous Raman and neutron vibrational spectroscopy on samples of material at the VISION neutron vibrational spectrometer of the Spallation Neutron Source at Oak Ridge National Laboratory. This equipment holds material samples in the neutron beam within the cryogenic environment of the VISION spectrometer, allowing for samples to be studied at temperatures as low as 5 K. It also provides the capability for gas to be loaded to or evacuated from the sample while it is loaded at VISION. The optical components for directing and filtering light are located within the cryogenic volume, in physical proximity to the sample. We describe the construction of this sample holder and discuss our first measurements of simultaneous Raman and neutron vibrational spectra. The samples that we report on were of 4-nitrophenol at a temperature of 20 K and of cryogenic hydrogen of a number of different orthohydrogen fractions.
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http://dx.doi.org/10.1063/1.4997933 | DOI Listing |
Sci Adv
January 2025
Department of Mechanical and Industrial Engineering, University of Massachusetts Amherst, Amherst, MA 01003, USA.
To push upper boundaries of thermal conductivity in polymer composites, understanding of thermal transport mechanisms is crucial. Despite extensive simulations, systematic experimental investigation on thermal transport in polymer composites is limited. To better understand thermal transport processes, we design polymer composites with perfect fillers (graphite) and defective fillers (graphite oxide), using polyvinyl alcohol (PVA) as a matrix model.
View Article and Find Full Text PDFAdv Mater
December 2024
Department of Materials and Environmental Chemistry, Stockholm University, Stockholm, SE-106 91, Sweden.
Superinsulating nanofibrillar cellulose foams have the potential to replace fossil-based insulating materials, but the development is hampered by the moisture-dependent heat transport and the lack of direct measurements of phonon transport. Here, inelastic neutron scattering is used together with wide angle X-ray scattering (WAXS) and small angle neutron scattering to relate the moisture-dependent structural modifications to the vibrational dynamics and phonon transport and scattering of cellulose nanofibrils from wood and tunicate, and wood cellulose nanocrystals (W-CNC). The moisture interacted primarily with the disordered regions in nanocellulose, and WAXS showed that the crystallinity and coherence length increased as the moisture content increased.
View Article and Find Full Text PDFPhys Rev Lett
November 2024
Ruđer Bošković Institute, HR-10000 Zagreb, Croatia.
In this Letter we report on effects of nucleon-nucleon correlations probed in nucleon transfer reactions with heavy ions. We measured with high efficiency and resolution a complete set of observables for neutron transfer channels in the ^{206}Pb+^{118}Sn system employing a large solid angle magnetic spectrometer, which allowed us to study a wide range of internuclear distances via a detailed excitation function. The coupled channel theory, based on an independent particle transfer mechanism, follows the experimental transfer probabilities for one- and two-neutron pick-up and stripping channels.
View Article and Find Full Text PDFAngew Chem Int Ed Engl
December 2024
Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
A recent finding shows that lattice deformation could transform the mixed electronic/hydride (H) conducting lanthanum trihydride (LaH) to a superionic H conductor. Such a feature would enable the development of a brand-new all-solid-state hydride ion battery. It is essential to elucidate the mechanism of such a phenomenon.
View Article and Find Full Text PDFNatl Sci Rev
December 2024
Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
Crystalline solids exhibiting inherently low lattice thermal conductivity ( ) are of great importance in applications such as thermoelectrics and thermal barrier coatings. However, cannot be arbitrarily low and is limited by the minimum thermal conductivity related to phonon dispersions. In this work, we report the liquid-like thermal transport in a well-ordered crystalline CsAgTe, which exhibits an extremely low value of ∼0.
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