Quantum effects in the noninertial Brownian motion of a particle in a double well potential are treated via a semiclassical Smoluchowski equation for the time evolution of the reduced Wigner distribution function in configuration space allowing one to evaluate the position correlation function, its characteristic relaxation times, and dynamic susceptibility using matrix continued fractions and finite integral representations in the manner of the classical Smoluchowski equation treatment. Reliable approximate analytic solutions based on the exponential separation of the time scales of the fast intrawell and slow overbarrier relaxation processes are given. Moreover, the effective and the longest relaxation times of the position correlation function yield accurate predictions of both the low and high frequency relaxation behavior. The low frequency part of the dynamic susceptibility associated with the Kramers escape rate behaves as a single Lorentzian with characteristic frequency given by the quantum-mechanical reaction rate solution of the Kramers problem. As a particular example, quantum effects in the stochastic resonance are estimated.
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http://dx.doi.org/10.1063/1.3211021 | DOI Listing |
Nat Commun
January 2025
Hefei National Research Center for Physical Sciences at the Microscale, Department of Physics and CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics, University of Science and Technology of China, Hefei, China.
Dielectric capacitors are vital for modern power and electronic systems, and accurate assessment of their dielectric properties is paramount. However, in many prevailing reports, the fringing effect near electrodes and parasitic capacitance in the test circuit were often neglected, leading to overrated dielectric performances. Here, the serious impacts of the fringing effect and parasitic capacitance are investigated both experimentally and theoretically on different dielectrics including AlO, SrTiO, etc.
View Article and Find Full Text PDFInt J Biol Macromol
January 2025
Department of Materials Engineering, Materials and Energy Research Center, Dezful Branch, Islamic Azad University, Dezfool, Iran.
Polymer-based nanocomposite coatings that are enhanced with nanoparticles have gained recognition as effective materials for antibacterial purposes, providing improved durability and biocidal effectiveness. This research introduces an innovative chitosan-based polymer nanocomposite, enhanced with titanium oxide nanopowders and carbon quantum dots. The material was synthesized via the sol-gel process and applied to 316L stainless steel through dip-coating.
View Article and Find Full Text PDFFood Chem
January 2025
State Key Laboratory of Food Nutrition and Safety, Tianjin University of Science & Technology, 29 The Thirteenth Road, Tianjin Economy and Technology Development Area, Tianjin 300457, PR China; Research Institute of Food Crops, Xinjiang Academy of Agricultural Sciences, No.403 Nanchang Road, Urumqi, Xinjiang 830091, PR China. Electronic address:
A novel electrochemiluminescence (ECL) sensor based on eco-friendly CN QDs was constructed for the ultrasensitive detection of VK. The synthesized NiCo nanocages (NiCo NCs) with large specific surface area and high catalytic activity were used to effectively load CN QDs, forming the nanocomposites (NiCo NCs@CN QDs) with good luminescent properties. After grafting NiCo NCs@CN QDs onto poly-L-cysteine film, the ECL system achieved multiple signal amplification, which was due to the fact that poly-L-cysteine as a co-reactant accelerator sped up the generation of more SO from SO.
View Article and Find Full Text PDFJ Fluoresc
January 2025
Department of Chemistry, The University of Burdwan, Golapbag, Burdwan, 713104, India.
Nitrogen doped Carbon Quantum Dots (NCQDs) have been synthesized using most economical and easiest hydrothermal process. Here, N-phenyl orthophenylenediamine and citric acid were utilised as a source of nitrogen and carbon for the preparation of NCQDs. The synthesized NCQDs were characterized using experimental techniques like UV - Vis absorption, FT-IR, transmission electron microscopy (TEM), X-ray Diffraction (XRD), EDX, dynamic light scattering (DLS), fluorimeter and time resolved fluorescence spectroscopy.
View Article and Find Full Text PDFACS Nano
January 2025
Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
Controlling the light emitted by individual molecules is instrumental to a number of advanced nanotechnologies ranging from super-resolution bioimaging and molecular sensing to quantum nanophotonics. Molecular emission can be tailored by modifying the local photonic environment, for example, by precisely placing a single molecule inside a plasmonic nanocavity with the help of DNA origami. Here, using this scalable approach, we show that commercial fluorophores may experience giant Purcell factors and Lamb shifts, reaching values on par with those recently reported in scanning tip experiments.
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