In this paper we present inelastic X-ray scattering experiments in a diamond anvil cell and molecular dynamic simulations to investigate the behavior of phononic excitations in liquid Ar. The spectra calculated using molecular dynamics were found to be in a good agreement with the experimental data. Furthermore, we observe that, upon temperature increases, a low-frequency transverse phononic gap emerges while high-frequency propagating modes become evanescent at the THz scale. The effect of strong localization of a longitudinal phononic mode in the supercritical phase is observed for the first time. The evidence for the high-frequency transverse phononic gap due to the transition from an oscillatory to a ballistic dynamic regimes of motion is presented and supported by molecular dynamics simulations. This transition takes place across the Frenkel line thermodynamic limit which demarcates compressed liquid and non-compressed fluid domains on the phase diagram and is supported by calculations within the Green-Kubo phenomenological formalism. These results are crucial to advance the development of novel terahertz thermal devices, phononic lenses, mirrors, and other THz metamaterials.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4725891 | PMC |
| http://dx.doi.org/10.1038/srep19469 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Terahertz scanning near-field optical microscopy for biomedical detection: Recent advances, challenges, and future perspectives.
Biotechnol Adv
December 2024
Center of Super-Resolution Optics and Chongqing Engineering Research Center of High-Resolution and Three-Dimensional Dynamic Imaging Technology, Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China; Chongqing School, University of Chinese Academy of Sciences, Chongqing 400714, China. Electronic address:
Terahertz (THz) radiation is widely recognized as a non-destructive, label-free, and highly- sensitive tool for biomedical detections. Nevertheless, its application in precision biomedical fields faces challenges due to poor spatial resolution caused by intrinsically long wavelength characteristics. THz scanning near-field optical microscopy (THz-SNOM), which surpasses the Rayleigh criterion, offers micrometer and nanometer-scale spatial resolution, making it possible to perform precise bioinspection with THz imaging.
View Article and Find Full Text PDFObservation of Boson Peak of Fragile Baltic Amber Glass by Terahertz Time-Domain Spectroscopy.
Materials (Basel)
December 2024
Department of Materials Science, University of Tsukuba, Tsukuba 305-8573, Ibaraki, Japan.
Amber is a fragile (in Angell's classification) natural glass that has performed maturation processes over geological time. The terahertz dynamics of Baltic amber that was about 40 million years old were studied by terahertz time-domain spectroscopy (THz-TDS) in the frequency range of 0.2 and 6.
View Article and Find Full Text PDFArticle Synopsis
- Terahertz (THz) radar is beneficial for its high frequency and strong penetration ability, making it suitable for fields like aerospace and non-destructive testing, but current systems struggle with large-scale detection due to complexity and costs.
- A new radar system using a one-dimensional photonic crystal and spintronic technology improves THz radar signals, achieving a signal-to-noise ratio of about 58 dB and bandwidth over 5 THz.
- This innovative design allows for high-quality, uniform THz waves over a 4-inch radius, paving the way for advanced radar imaging useful in areas such as aerospace engineering, stealth testing, and 3D reconstruction.
Aluminium nanoparticle-based ultra-wideband high-performance polarizer.
Heliyon
October 2024
Department of Electrical and Electronic Engineering, Bangladesh University of Engineering and Technology, Dhaka, 1205, Bangladesh.
Article Synopsis
- - The study focuses on the development of high-quality nanoscale wideband polarizers using aluminum (Al) dimer nanostructures, which have shown superior performance compared to traditional wire-grid designs, especially in the near-infrared (NIR) and terahertz (THz) ranges.
- - A novel nanoparticle polarizer design features semi-immersed Al nano-dimers on a calcium fluoride (CaF) substrate, achieving an impressive extinction ratio exceeding 55 dB across a 0.2 to 9 THz range, with peak values of 60 dB in the THz region.
- - The research evaluates key performance parameters including insertion loss (about 1 dB) and overall
High-quality CMOS compatible n-type SiGe parabolic quantum wells for intersubband photonics at 2.5-5 THz.
Nanophotonics
April 2024
Dipartimento di Scienze, Università; degli Studi Roma Tre, Viale G. Marconi 446, Roma 00146, Italy.
A parabolic potential that confines charge carriers along the growth direction of quantum wells semiconductor systems is characterized by a single resonance frequency, associated to intersubband transitions. Motivated by fascinating quantum optics applications leveraging on this property, we use the technologically relevant SiGe material system to design, grow, and characterize n-type doped parabolic quantum wells realized by continuously grading Ge-rich Si Ge alloys, deposited on silicon wafers. An extensive structural analysis highlights the capability of the ultra-high-vacuum chemical vapor deposition technique here used to precisely control the quadratic confining potential and the target doping profile.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!