Free electron model

About: Free electron model is a research topic. Over the lifetime, 4678 publications have been published within this topic receiving 103535 citations.

Influence of Hot Electron Scattering and Electron-Phonon Interactions on Thermal Boundary Conductance at Metal/Nonmetal Interfaces

Abstract: It has recently been demonstrated that under certain conditions of electron nonequilibrium, electron to substrate energy coupling could represent a unique mechanism to enhance heat flow across interfaces. In this work, we present a coupled thermodynamic and quantum mechanical derivation of electron–phonon scattering at free electron metal/ nonmetal substrate interfaces. A simplified approach to the Fermi’s Golden Rule with electron energy transitions between only three energy levels is adopted to derive an electron–phonon diffuse mismatch model, that account for the electron–phonon thermal boundary conductance at metal/insulator interfaces increases with electron temperature. Our approach demonstrates that the metal-electron/nonmetal phonon conductance at interfaces can be an order of magnitude larger than purely phonon driven processes when the electrons are driven out of equilibrium with the phonons, consistent with recent experimental observations. [DOI: 10.1115/1.4027785]

Ultrafast x-ray and electron scattering of free molecules: A comparative evaluation.

Abstract: Resolving gas phase molecular motions with simultaneous spatial and temporal resolution is rapidly coming within the reach of x-ray Free Electron Lasers (XFELs) and Mega-electron-Volt (MeV) electron beams. These two methods enable scattering experiments that have yielded fascinating new results, and while both are important methods for determining transient molecular structures in photochemical reactions, it is important to understand their relative merits. In the present study, we evaluate the respective scattering cross sections of the two methods and simulate their ability to determine excited state molecular structures in light of currently existing XFEL and MeV source parameters. Using the example of optically excited N-methyl morpholine and simulating the scattering patterns with shot noise, we find that the currently achievable signals are superior with x-ray scattering for equal samples and on a per-shot basis and that x-ray scattering requires fewer detected signal counts for an equal fidelity structure determination. Importantly, within the independent atom model, excellent structure determinations can be achieved for scattering vectors only to about 5 A−1, leaving larger scattering vector ranges for investigating vibrational motions and wavepackets. Electron scattering has a comparatively higher sensitivity toward hydrogen atoms, which may point to applications where electron scattering is inherently the preferred choice, provided that excellent signals can be achieved at large scattering angles that are currently difficult to access.

On the conductance of finite systems in the ballistic regime: Dependence on Fermi energy, magnetic field, frequency, and disorder

Abstract: It is shown that the dc-conductance of a ballistically behaving electron system of a finite width is quantised in units ofe2/h. The quantisation is independent of the length of the system, and can be observed experimentally by changing the Fermi energy, the geometrical width, and the magnetic field, alternatively. Two novel quantum phenomena are predicted. In the presence of weak disorder there are anti-resonances which separate neighboring conductance plateaus. The ac-conductance shows oscillations which can be assigned to interference of free electron states.

Simulation of tuning of one-dimensional photonic crystals in the presence of free electrons and holes

Abstract: We simulate the tuning of the optical reflectance in one-dimensional photonic crystals. Two monolithic superlattices are considered: Intrinsic InSb/air and extrinsic n-type Si/air, both with high densities of free-electron plasmas. The tuning is achieved, respectively, by varying the temperature and the donor concentration. In our modeling, we have taken into account both dispersion and absorption for the electrons, the holes, and the phonons. Our realistic simulation demonstrates that very strong sensitivity of the optical response is achievable.