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Coulomb interaction-induced jitter amplification in RF-compressed high-brightness electron source ultrafast electron diffraction
摘要： We have theoretically and experimentally demonstrated an RF compression-based jitter-amplification effect in high-brightness electron source ultrafast electron diffraction (UED), which degrades the temporal resolution significantly. A detailed analysis and simulations reveal the crucial role of the longitudinal and transverse Coulomb interaction for this jitter-amplification effect, which accord very well with experimental results. An optimized compact UED structure for full compression has been proposed, which can suppress the jitter by half and improve the temporal resolution to sub-100 fs. This Coulomb interaction-induced jitter amplification exists in nearly the whole ultrafast physics field where laser-electron synchronization is required. Moreover, it cannot be suppressed completely. The quantified explanation for the mechanism and optimization provides important guidance for photocathode accelerators and other compression-based ultrashort electron pulse generation and precise control.
关键词： system optimization,jitter amplification,RF compression,high-brightness electron source,ultrafast electron diffraction,Coulomb interaction
更新于2025-09-23 15:21:21
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Spectral weights of mixed coupled plasmon modes in Dirac electron systems with different dimensionality
摘要： We study the effects of coupling between plasmon modes by the long-range Coulomb electron-electron interaction for a system consisting of a two-dimensional (2D) system of Dirac electrons embedded in three-dimensional (3D) Dirac semimetal. We obtain the dispersions of coupled plasmon modes for various separations of the subsystems. The coupled modes become more separated with decreasing the separation between two subsystems as the coupling increases due to the enhanced Coulomb interaction between electrons from different subsystems. We also demonstrate how the coupling affects the spectral weights of the obtained modes in two subsystems for different separations. In the 2D subsystem both coupled modes have finite weights for small wavenumbers, while for large wavenumbers only the upper mode persists. On the other hand, in the bulk this mode takes most of the spectral weight for small wavenumbers, while for large wavenumbers the lower mode is more pronounced.
关键词： plasmon modes,Coulomb interaction,spectral weights,Dirac electron systems
更新于2025-09-23 15:21:01
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Multi-electron anisotropic quantum dots/TMDCs/CNT families under magnetic field: analytical treatment to first Brillouin zone by Fermi liquid model
摘要： Acute Coulomb interaction of the two-dimensional systems has drawn special attention due to its unusual logarithmic Green function expansion. As the number of electrons (N) increases, Pauli Exclusion principle emerges inevitably with rapidly growing electronic correlations. Quantum dot, Transition metal dichalcogenides (TMDC) and Carbon nanotube (CNT) families of 2-D anisotropic mesoscopic systems are rich habitats of electrons. Schr?dinger equations of such electrons in electrical confinement and transverse magnetic field can be recast in self-adjoint Whittaker-M functions facilitating each Coulomb interaction to terminable, exact and single summed Lauricella function via Chu-Vandermonde identity. For N = 3, 4, 5, 6, . . . 20, multipoles of Green function expansion also succumb to terminable, single-summed, analytical integrals by inserting discretised closure relations. Thus, multi-configuration Slater determinantal states are employed for strong correlation of Fermi liquid model of first Brillouin zone (FBZ) within giga-units of reciprocal lattices (mesoscopic scale). Chemical potential, addition energies of WS2, GaAs and model systems of dielectric constant = 1.0 have set benchmark at low and high confinement potentials, as a function of magnetic field and density of electrons. Because of sharp falls in surface integrals of both Newman and Dirichlet forms of Green function, Coulomb interaction takes to (or leads to) multipole expansion of generic coordinates. Formation of composite-fermions may be anticipated. At the most, octupole is sufficient for the convergence.
关键词： Lauricella Functions,multi-configuration slater determinant,Fermi liquid model,strong Coulomb interaction,quantum dots/TMDC
更新于2025-09-23 15:21:01
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Quantum dot exciton dephasing by Coulomb interaction: A fermionic analog of the independent boson model
摘要： The time evolution of a quantum dot exciton in Coulomb interaction with wetting layer carriers is treated using an approach similar to the independent boson model. The role of the polaronic unitary transform is played by the scattering matrix, for which a diagrammatic, linked cluster expansion is available. Similarities and differences to the independent boson model are discussed. A numerical example is presented.
关键词： independent boson model,exciton,scattering matrix,Coulomb interaction,quantum dot
更新于2025-09-23 15:19:57
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Universal Hall Coefficient Correction in Strongly Coupled Cr‐SiO <sub/>2</sub> Nanogranular Metals
摘要： The microstructure and electrical transport properties of Crx(SiO2)1?x nanogranular films with Cr volume faction x ≈ 0.67 and 0.72 are systematically investigated. The transmission electron microscopy images and elemental mappings indicate that the films are quite inhomogeneous: some Cr granules directly connect to others while some Cr granules with size ≈1–3 nm disperse in the SiO2 dielectric matrix. For each film, the Hall coefficient RH varies linearly with the natural logarithm of temperature, i.e., ΔRH ∝ lnT, above ≈60 K, saturates at ≈60 K, and retains the saturating value below ≈60 K. The temperature dependence of Hall coefficient can be explained by the recent theory in granular metals and originates from virtual diffusion of electrons through the metallic granules. For the conductivity σ, a robust Δσ ∝ √T is observed from ≈50 down to 2 K. The behavior of the conductivity stems from the “Altshuler–Aronov” correction, whose influence on the Hall coefficient is not present in the films.
关键词： Hall transport,electrical transport,quantum effects of Coulomb interaction,granular films
更新于2025-09-19 17:13:59
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Polarizability of germanium quantum dots with spatially separated electrons and holes in Ge/Si heterostructures
摘要： In the framework of dipole approximation, it is shown that the quantities (the oscillator strengths of transitions, the dipole moments for transitions, and the polarizability) describing optical absorption on surface exciton states with spatially separated electrons and holes (the hole moves in the germanium quantum dot and the electron is localised over the spherical interface of the silicon quantum dot matrix) assume giant values considerably exceeding the typical values of the corresponding quantities for semiconductors under the action of low-intensity light.
关键词： transition dipole moments,polarizability,oscillator strength,Spatially indirect excitons,quantum dots,polarization interaction,Coulomb interaction
更新于2025-09-16 10:30:52
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(3-phenylpyridin-1-ium)SbI4: Coulomb interaction-assembled Lead-free hybrid perovskite-like semiconductor
摘要： The environmental toxicity of Pb in inorganic-organic hybrid perovskite presents a major hurdle to commercialization, which trigger intense research on exploring Pb-free alternatives. Soft interaction, especially Coulomb interaction not only enriching the synthesis strategy but endowing unique property to the derived materials, is appealing for constructing Pb-free alternatives, however is less reported. We herein demonstrate the construction of a Sb-based hybrid perovskite-like semiconductor (3-phenylpyridin-1-ium)SbI4 (denoted as 3ppi-SbI4) via the “Coulomb interaction strategy”. Therein, the zigza (SbI4)– chains interact with the 3ppi countercations through Coulomb interaction-only in the crystal lattice. It has good moisture, sunlight and UV light stabilities. Further, 3ppi-SbI4 exhibits excellent light absorption, direct band-gap feature, good photoconduction, and excellent repeatability of photocurrent, which all imply its potential as a Pb-free light-absorbing candidate for optoelectronic application. Theoretical calculations disclose that the photo response is mainly ascribe to the electron transitions within (SbI4)– chains, as well as between inorganic and organic moieties.
关键词： hybrid perovskite,photoconduction,Antimony,Coulomb interaction,semiconductor
更新于2025-09-12 10:27:22