Colloidal nanocrystals are successfully used as nanoscale building blocks for creating hierarchical solids with structures that range from amorphous networks to sophisticated periodic superlattices. Recently, it has been observed that these superlattices exhibit collective vibrations, which stem from the correlated motion of the nanocrystals, with their surface-bound ligands acting as molecular linkers. In this Perspective, we describe the work so far on collective vibrations in nanocrystal solids and their as-of-yet untapped potential for phononic applications. With the ability to engineer vibrations in the hypersonic regime through the choice of nanocrystal and linker composition, as well as by controlling their size, shape and chemical interactions, such superstructures offer new opportunities for phononic crystals, acoustic metamaterials and optomechanical systems.
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http://dx.doi.org/10.1038/s41563-022-01438-4 | DOI Listing |
Soft Matter
January 2025
Physics Department, Wesleyan University, Middletown, CT 06459, USA.
We examine the collective motion in computational models of a two-dimensional dusty plasma crystal and a charged colloidal suspension as they approach their respective melting transitions. To unambiguously identify rearrangement events in the crystal, we map the trajectory of configurations from an equilibrium molecular dynamics simulation to the corresponding sequence of configurations of local potential energy minima ("inherent structures"). This inherent structure (IS) trajectory eliminates the ambiguity that arises from localized vibrational motion.
View Article and Find Full Text PDFAmino Acids
January 2025
Faculty of Natural Sciences, University of SS Cyril and Methodius, 91701, Trnava, Slovakia.
Four aliphatic amino acids-α-aminobutyric acid (AABA), β-aminobutyric acid (BABA), α-aminoisobutyric acid (AAIBA) and β-aminoisobutyric acid (BAIBA) were investigated in water as a solvent by two quantum chemical methods. B3LYP hybrid version of DFT was used for geometry optimization and a full vibrational analysis of neutral molecules, their cations and anions in the canonical and zwitterionic forms (6 forms for each species). Ab initio DLPNO-CCSD(T) method was applied in the geometry pre-optimized by B3LYP.
View Article and Find Full Text PDFChem Commun (Camb)
January 2025
Department of Chemistry, Quantum Chemistry, TU Darmstadt, Peter-Grünberg-Str. 4, 64287 Darmstadt, Germany.
The two key parameters extracted from Mössbauer spectroscopy, isomer shift and quadrupole splitting, have well-known temperature dependencies. While the behavior of the values following a temperature change has long been known, its microscopic origins are less clear. For quantum chemical calculations - formally representing the situation at 0 K - significant discrepancies with the experiment can arise, especially at elevated temperatures.
View Article and Find Full Text PDFJ Phys Chem B
January 2025
Chemical, Biological and Macromolecular Sciences, S. N. Bose National Centre for Basic Sciences, J. D. Block, Sec.III, Salt Lake, Kolkata, West Bengal 700 098, India.
We investigated the temperature dependence of the intermolecular dynamics, including intermolecular vibrations and collective orientational relaxation, of one of the most typical deep eutectic solvents, reline, using femtosecond Raman-induced Kerr effect spectroscopy (fs-RIKES), subpicosecond optical Kerr effect spectroscopy (ps-OKES), and molecular dynamics (MD) simulations. According to fs-RIKES results, the temperature-dependent intermolecular vibrational band peak at ∼90 cm exhibited a redshift with increasing temperature. The density-of-state (DOS) spectrum of reline by MD simulations reproduced this fs-RIKES spectral feature.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Communications and Electronics, Delta Higher Institute of Engineering and Technology, Mansoura, 35111, Egypt.
The research study objective seeks to improve the efficiency of wind turbines using state-of-the-art techniques in the domain of ML, making wind energy the key player in fashioning a favorable future. Wind Turbine Health Monitoring (WTHM) is typically achieved through either vibration analysis or by using Supervisory Control and Data Acquisition (SCADA) data of wind turbines, wherein conventional fault pattern identification is a time-consuming, guesswork process. This work proposed an intelligent automated approach to early fault detection through the implementation of the HARO (Huber Adam Regression Optimizer) model, which combines Transformer networks with Lasso Regression and the Adam optimizer.
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