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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.
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TL;DR: For hydrogen, the electronic stopping power S is found to be perfectly proportional to velocity, as expected for a free electron gas, but for He, S shows a transition between two distinct regimes, in both of which S is velocity proportional-however, with remarkably different slopes.
Abstract: Electronic energy loss of light ions transmitted through nanometer films of Al has been studied at very low ion velocities. For hydrogen, the electronic stopping power S is found to be perfectly proportional to velocity, as expected for a free electron gas. For He, the same is anticipated, but S shows a transition between two distinct regimes, in both of which S is velocity proportional-however, with remarkably different slopes. This finding can be explained as a consequence of charge exchange in close encounters between He and Al atoms, which represents an additional energy loss channel.
48 citations
TL;DR: The extraordinarily high SCS observed for protons in Ta and Gd cannot be understood in terms of a free electron gas model, but are related to the high densities of both occupied and unoccupied electronic states in these metals.
Abstract: Measurements of how slow protons stop in tantalum and gadolinium show that the process is dependent on the density of states.
48 citations
12 Nov 2020
TL;DR: In this article, a femtosecond-switchable inelastic beam splitter was demonstrated, where coherent optical phase modulation of 200-keV electrons at a thin electron-transparent membrane was used to prepare a high-purity three-dimensional momentum superposition state, which was characterized in energy and momentum space.
Abstract: This paper demonstrates a laser-based and femtosecond-switchable inelastic electron beam splitter. Coherent optical phase modulation of 200-keV electrons at a thin electron-transparent membrane is used to prepare a high-purity three-dimensional momentum superposition state, which is characterized in energy and momentum space.
48 citations
TL;DR: It is demonstrated that the relative composition of free electrons and H2O2 in the optical breakdown plasma may be controlled by changing the pulse energy and duration, which may make it possible to tune the size and dispersity of AuNPs and other metal nanoparticle products synthesized with femtosecond laser-based methods.
Abstract: Free electrons and H2O2 formed in an optical breakdown plasma are found to directly control the kinetics of [AuCl4]− reduction to form Au nanoparticles (AuNPs) during femtosecond laser-assisted synthesis of AuNPs. The formation rates of both free electrons and H2O2 strongly depend on the energy and duration of the 800 nm laser pulses over the ranges of 10–2400 μJ and 30–1500 fs. By monitoring the conversion of [AuCl4]− to AuNPs using in situ UV–vis spectroscopy during laser irradiation, the first- and second-order rate constants in the autocatalytic rate law, k1 and k2, were extracted and compared to the computed free electron densities and experimentally measured H2O2 formation rates. For laser pulse energies of 600 μJ and lower at all pulse durations, the first-order rate constant, k1, was found to be directly proportional to the theoretically calculated plasma volume, in which the electron density exceeds the threshold value of 1.8 × 1020 cm–3. The second-order rate constant, k2, was found to correlate...
48 citations
TL;DR: In this article, a double quantum dot (2qd) system connected in a series with electrodes is studied by means of nonequilibrium Green functions and using the equation of motion method, in which all electron correlations in the 2qd are treated exactly.
Abstract: Coherent electronic transport through a double quantum dot (2qd) system connected in a series with electrodes is studied by means of nonequilibrium Green functions and using the equation of motion method, in which all electron correlations in the 2qd are treated exactly. For moderate Coulomb interactions we predict features in a conductance characteristics resulting from transmission through triplet states, which can be strongly activated for larger source-drain voltages. The analysis of the spin-spin correlation functions shows strong antiferromagnetic correlations arising from transport through the singlet state and a reduction of the total magnetic moment. However, when the transmission channel corresponding to the triplet state becomes activated the antiferromagnetic correlations are much weaker, the spins behave as free electrons spins and strongly fluctuate. We speculate that this effect can be seen in wide range of a gate voltage for a double electron occupancy of the 2qd.
47 citations