Article
Multidisciplinary Sciences
Galina L. Klimchitskaya, Constantine C. Korikov, Vladimir M. Mostepanenko, Oleg Yu. Tsybin
Summary: This study investigates the out-of-thermal-equilibrium Casimir-Polder force between nanoparticles and dielectric substrates coated with gapped graphene using the Dirac model and the polarization tensor formalism. The results show that the presence of a substrate can increase the magnitude of the nonequilibrium force. The temperature of the graphene-coated substrate also affects the force magnitude.
Article
Physics, Nuclear
G. L. Klimchitskaya, U. Mohideen, V. M. Mostepanenko
Summary: This article reviews the Casimir effect in graphene systems, with a focus on the large thermal correction to the Casimir force predicted at short separations between test bodies. Computational results are presented for the Casimir pressure and thermal correction in both pristine graphene and real graphene sheets, obtained using the exact polarization tensor. Two experiments are described, which measure the gradient of the Casimir force between an Au-coated sphere and graphene-coated substrates using a modified atomic force microscope cantilever-based technique. The measurement data from both experiments are shown to be in agreement with theoretical predictions, and the second experiment demonstrates the predicted large thermal effect at short separations. The potential implications of this result for resolving long-standing problems in Casimir physics are discussed.
INTERNATIONAL JOURNAL OF MODERN PHYSICS A
(2022)
Article
Optics
G. L. Klimchitskaya, V. M. Mostepanenko
Summary: The paper introduces a new phenomenological dielectric function for metals, which exhibits similar response as the standard Drude model for propagating waves but different response for evanescent waves. Using this function, the effective Casimir pressure and force between different test bodies are calculated and compared with measurement data. The results show that the predictions of the Lifshitz theory using the dissipative nonlocal response functions are in good agreement with the measurement data.
Article
Materials Science, Multidisciplinary
G. L. Klimchitskaya, V. M. Mostepanenko, E. N. Velichko
Summary: The presence of a graphene sheet can change the Casimir pressure in peptide films deposited on metallic substrates from repulsive to attractive. The effects are influenced by the chemical potential and energy gap of the graphene sheet.
Article
Chemistry, Physical
Haining Li, Bing Yang, Biao Yu, Nan Huang, Lusheng Liu, Jiaqi Lu, Xin Jiang
Summary: Treatment of hydrogen plasma on silicon nanowires, followed by coatings of nanocrystalline diamond and multilayer graphene, enables enhanced Raman signals with reduced fluorescent background. The graphene-coated nanowires show lower fluorescent background than diamond-coated ones, with a minimum detection limit of 10(7) mol/L and an enhancement factor exceeding 10(4). The stable Raman enhancement is attributed to hydrogen-terminated graphene and the nanowire structure, independent of graphene layers and maintaining stability after exposure to the atmosphere for a month.
APPLIED SURFACE SCIENCE
(2021)
Article
Chemistry, Multidisciplinary
Galina L. Klimchitskaya, Constantine C. Korikov, Vladimir M. Mostepanenko, Oleg Yu. Tsybin
Summary: The nonequilibrium dispersion force acting on nanoparticles on the source side of a gapped graphene sheet is investigated in this study. The dispersion force is calculated as a function of separation at different mass-gap parameters using the generalization of the Lifshitz theory. The response of the graphene sheet to quantum and thermal fluctuations is described using the polarization tensor in (2+1)-dimensional space-time based on the Dirac model. The nontrivial impact of the mass-gap parameter on the nonequilibrium dispersion force, as well as its potential applications in micro- and nanodevice design, are discussed.
APPLIED SCIENCES-BASEL
(2023)
Article
Chemistry, Multidisciplinary
Peizong Chen, Ningning Zhang, Kun Peng, Lijian Zhang, Jia Yan, Zuimin Jiang, Zhenyang Zhong
Summary: An innovative strategy has been developed to realize artificial graphene on Si substrates by fabricating a honeycomb lattice of Au nanodisks, resulting in unique features such as nonlinear current-voltage curves and conductance phase transitions. These characteristics are interpreted by a model based on the Coulomb blockade effect, resonant tunneling, and hole coupling within the artificial graphene.
Article
Chemistry, Multidisciplinary
Zhenming Wang, Jianxun Liu, Jiawei Wang, Zongjun Ma, Delai Kong, Shouzhen Jiang, Dan Luo, Yan Jun Liu
Summary: This paper presents a cost-effective, large-sized, and highly reproducible SERS substrate prepared by nanosphere lithography technique. By manipulating the geometry of the Ag metasurface deposited on the substrate and coating a thin layer of graphene oxide, high enhancement factor and low detection limit of SERS performance have been achieved. Experimental results demonstrate the potential application value of this method for trace detection in fields like food safety control and environmental monitoring.
Article
Mechanics
Nikhil Sharma, Deepak Jain, Bikramjit Sharma, Romesh C. Batra
Summary: Graphene-polymer nanocomposite coatings are used to enhance thermal conductivity. The study quantifies the improvement provided by coatings made from graphene nano platelets (GNPs) with different aspect ratios and mass fractions in an epoxy matrix. The results show that biofilm hinders heat exchange the most, while unidirectional oriented GNPs/epoxy coating hinders the least. The compressive normal stress induced at the interface between the coating and the steel plate can prevent delamination.
COMPOSITE STRUCTURES
(2023)
Article
Materials Science, Multidisciplinary
Galina L. Klimchitskaya, Vladimir M. Mostepanenko
Summary: This study investigates the Casimir-Polder force acting on atoms and nanoparticles at large separations from real graphene sheets with energy gaps and chemical potentials, using the Lifshitz theory. Reflective coefficients, expressed through the polarization tensor of graphene, are derived from first principles of thermal quantum field theory. The study shows that for graphene, separations at which the zero-frequency term of the Lifshitz formula contributes more than 99% of the total Casimir-Polder force are smaller than the standard thermal length. The classical limit for graphene may be reached at larger separations depending on energy gaps and chemical potentials, beyond the limit determined by the zero-frequency term.
C-JOURNAL OF CARBON RESEARCH
(2023)
Article
Crystallography
Hanna Bandarenka, Aliaksandr Burko, Diana Laputsko, Lizaveta Dronina, Nikolai Kovalchuk, Alise Podelinska, Uladzislau Shapel, Anatoli I. Popov, Dmitry Bocharov
Summary: This study reveals a significant improvement in the surface-enhanced Raman scattering (SERS) activity of Ag/ZrO2 substrates covered with a few-layer graphene preliminary exposed to ultraviolet (UV) light. The few-layer graphene prevents the decomposition of dye molecules and improves the SERS activity of the substrates.
Article
Chemistry, Analytical
Bing Yan, Xiulan Ling, Renxian Li, Jianyong Zhang, Chenhua Liu
Summary: In this study, the optical force and torque on a graphene-coated gold nanosphere by a vector Bessel beam within the generalized Lorenz-Mie theory are investigated. The results show that the thickness of the graphene coating can adjust the peaks of the optical force and torque, while the half-cone angle and order can change the magnitude of the force and torque.
Article
Astronomy & Astrophysics
Nora Weickgenannt, Enrico Speranza, Xin-li Sheng, Qun Wang, Dirk H. Rischke
Summary: In this study, the Boltzmann equation and collision kernel for massive spin-1/2 particles were derived using the Wigner-function formalism and an expansion in powers of., The phase space was enlarged to include a variable related to spin degrees of freedom, which allowed for the reduction of transport equations to a scalar equation for independent components of the Wigner function. At next-to-leading order in., it was discovered that the collision kernel contains both local and nonlocal terms, with off-shell contributions being shown to cancel in the Boltzmann equation. It was also noted that this framework can be used to study spin-polarization phenomena induced by vorticity in heavy-ion collisions and condensed-matter systems.
Article
Materials Science, Multidisciplinary
Shuang Zhang, Dongjun He, Ping Huang, Fei Wang
Summary: This study observed unexpectedly large periodic moire patterns with a period of approximately 8.9 nm at the graphene/Al (111) interface for the first time. The moire pattern periodicity with respect to rotation orientation angle was evaluated by theoretical calculation, and the formation process was investigated via molecular dynamics simulations. The study proposed that thermal stress stimulated interface rotational growth may play a dominating role in the formation of the moire pattern.
MATERIALS & DESIGN
(2021)
Article
Chemistry, Physical
Qingchang Liu, Baoxing Xu
Summary: Strain engineering is used to tune the thermal properties of materials, and in this study, the interfacial thermal conductance of graphene on a soft substrate is regulated by manipulating the morphologies of graphene. The geometric features of graphene determine the thermal conductance, which decreases with increasing mechanical strain. This study provides a foundation for designing flexible and stretchable structures and devices with tunable thermal management performance.
Article
Astronomy & Astrophysics
Giuseppe Bimonte, Benjamin Spreng, Paulo A. Maia Neto, Gert-Ludwig Ingold, Galina L. Klimchitskaya, Vladimir M. Mostepanenko, Ricardo S. Decca
Summary: In this study, the differential Casimir force between an Au-coated sapphire sphere and Au-coated deep silicon trenches was determined using a micromechanical torsional oscillator. The results showed that the influence of surface roughness and edge effects on the measured force is negligible. The distribution of patch potentials and their impact on the measured force were characterized using Kelvin probe microscopy.
Article
Physics, Multidisciplinary
M. Liu, Y. Zhang, G. L. Klimchitskaya, V. M. Mostepanenko, U. Mohideen
Summary: The experimental confirmation of the unusually big thermal effect at separations below 1 μm for graphene suggests that its effective temperature is determined by the Fermi velocity rather than the speed of light.
PHYSICAL REVIEW LETTERS
(2021)
Editorial Material
Astronomy & Astrophysics
Nazar R. Ikhsanov, Galina L. Klimchitskaya, Vladimir M. Mostepanenko
Article
Multidisciplinary Sciences
Galina L. Klimchitskaya, Vladimir M. Mostepanenko, Oleg Yu Tsybin
Summary: The study focused on the Casimir pressure in peptide films deposited on different dielectric or metallic substrates. It was found that for dielectric-type semiconductor substrates, the thickness of the film determines whether the Casimir pressure is attractive or repulsive, depending on the percentage of water and the static dielectric permittivity of the semiconductor substrate; while for metallic-type semiconductor substrates, the Casimir pressure in peptide coatings is always repulsive.
Review
Physics, Multidisciplinary
Galina L. Klimchitskaya, Vladimir M. Mostepanenko
Summary: This article reviews the scientific pictures of the universe from ancient times to Albert Einstein and highlights Alexander Friedmann's prediction of the universe expansion. It discusses the experimental confirmation of this prediction and the implications it has on our understanding of the world.
Article
Materials Science, Multidisciplinary
G. L. Klimchitskaya, V. M. Mostepanenko, O. Yu. Tsybin
Summary: In this study, the nonequilibrium Casimir-Polder force between a nanoparticle and a graphene sheet kept at different temperatures was examined using the formalism of the polarization tensor in the framework of a Dirac model. The results demonstrate that the magnitude of the force increases with the temperature of the graphene sheet. The impact of nonequilibrium conditions on the force becomes smaller at larger separations. Our findings reveal that for a graphene sheet with a lower temperature than the environment, the attractive Casimir-Polder force vanishes at a specific separation distance and becomes repulsive at larger distances. This effect has potential applications in fundamental graphene research and force control in bioelectronic microdevices.
Article
Optics
G. L. Klimchitskaya, V. M. Mostepanenko
Summary: The paper introduces a new phenomenological dielectric function for metals, which exhibits similar response as the standard Drude model for propagating waves but different response for evanescent waves. Using this function, the effective Casimir pressure and force between different test bodies are calculated and compared with measurement data. The results show that the predictions of the Lifshitz theory using the dissipative nonlocal response functions are in good agreement with the measurement data.
Article
Astronomy & Astrophysics
G. L. Klimchitskaya, V. M. Mostepanenko
Summary: The Lifshitz theory of the Casimir force was extended to parallel magnetic metal plates with nonlocal dielectric responses. Results showed minimal differences in Casimir pressures between different nonlocal and local response functions at short separations but significant discrepancies at a few micrometer distances. The gradient of the Casimir force between Ni-coated surfaces of a sphere and a plate using alternative nonlocal response functions demonstrated good agreement with measurement data, providing insights for resolving longstanding problems in Casimir physics.
Article
Materials Science, Multidisciplinary
M. Liu, Y. Zhang, G. L. Klimchitskaya, V. M. Mostepanenko, U. Mohideen
Summary: The experimental results show that the polarization tensor of graphene can well describe the Casimir force gradient between an Au-coated hollow glass microsphere and a graphene-coated fused silica plate, while also excluding the theoretical predictions at zero temperature. The study also found a correlation between the thermal correction to the Casimir force gradient and factors such as substrate, energy gap, and chemical potential.
Article
Materials Science, Multidisciplinary
G. L. Klimchitskaya, V. M. Mostepanenko, E. N. Velichko
Summary: The presence of a graphene sheet can change the Casimir pressure in peptide films deposited on metallic substrates from repulsive to attractive. The effects are influenced by the chemical potential and energy gap of the graphene sheet.
