Controlling vibrations in solids is crucial to tailor their elastic properties and interaction with light. Thermal vibrations represent a source of noise and dephasing for many physical processes at the quantum level. One strategy to avoid these vibrations is to structure a solid such that it possesses a phononic stop band, that is, a frequency range over which there are no available elastic waves. Here we demonstrate the complete absence of thermal vibrations in a nanostructured silicon membrane at room temperature over a broad spectral window, with a 5.3-GHz-wide bandgap centred at 8.4 GHz. By constructing a line-defect waveguide, we directly measure gigahertz guided modes without any external excitation using Brillouin light scattering spectroscopy. Our experimental results show that the shamrock crystal geometry can be used as an efficient platform for phonon manipulation with possible applications in optomechanics and signal processing transduction.
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http://dx.doi.org/10.1038/s41565-022-01178-1 | DOI Listing |
Narra J
December 2024
Department of Pharmacochemistry, School of Pharmacy, Institut Teknologi Bandung, Bandung, Indonesia.
Gelatin is a versatile substance extensively used in medical and pharmaceutical industries for many applications, including capsule shells, X-ray film, infusion for plasma substitute, and the fabricating of artificial tissue. Fish scale gelatin is a profitable alternative source as a halal material despite its inferior quality. An addition of phenolic cross-linker may enhance the qualities of fish scale gelatin.
View Article and Find Full Text PDFAchiral metasurfaces with near-field optical chirality have attracted great attention in molecular sensing and chiral emission control. Here, the circular dichroism (CD) response of an achiral metasurface induced by spatially selective coupling with polymethyl methacrylate (PMMA) molecules is demonstrated. A designed achiral metasurface with a V-shaped resonator exhibits large optical chirality with a strongly dissymmetric distribution under circular polarization.
View Article and Find Full Text PDFJ Phys Condens Matter
January 2025
Department of Physics, The M S University of Baroda, Near Railway station, Sayajigunj, Vadodara, 390002, INDIA.
Controlling vibrational modes and energy gap by creating van der Waals (vdW) heterostructures through strain engineering is a novel approach to tailor the vibrational and electronic properties of two-dimensional (2D) materials. Numerous theoretical and experimental studies have significantly contributed to analysing the properties of transition metal dichalcogenides (TMDs), known for their multifunctional applications. In this study, we investigate the strain and stacking dependent vibrational properties of WSe2/MoSe2 and MoSe2/WSe2/MoSe2 vdW heterostructures using first-principles based density functional theory calculations.
View Article and Find Full Text PDFSmall Methods
January 2025
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, TN 37830, USA.
Understanding ferroelectric domain wall dynamics at the nanoscale across a broad range of timescales requires measuring domain wall position under different applied electric fields. The success of piezoresponse force microscopy (PFM) as a tool to apply local electric fields at different positions and imaging their changing position, together with the information obtained from associated switching spectroscopies has fueled numerous studies of the dynamics of ferroelectric domains to determine the impact of intrinsic parameters such as crystalline order, defects and pinning centers, as well as boundary conditions such as environment. However, the investigation of sub-coercive reversible domain wall vibrational modes requires the development of new tools that enable visualizing domain wall motion under varying applied fields with high temporal and spatial resolution while also accounting for spurious electrostatic effects.
View Article and Find Full Text PDFJ Phys Chem A
January 2025
Univ Rennes, CNRS, IPR (Institut de Physique de Rennes)─UMR 6251, F-35000 Rennes, France.
Chloronium (HCl) is an important intermediate of Cl-chemistry in space. The accurate knowledge of its collisional properties allows a better interpretation of the corresponding observations in interstellar clouds and, therefore, a better estimation of its abundance in these environments. While the ro-vibrational spectroscopy of HCl is well-known, the studies of its collisional excitation are rather limited and these are available for the interaction with helium atoms only.
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