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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: In this article, the field dependence of the relative decrease of fluorescence ΔF/F0 and of the photocurrent, i, is measured for dilute solutions of N,N,N′, N′•tetramethylparaphenylenediamine (TMPD) in 2,2,4•trimethylpentane (TMP) and tetramethylsilane(TMSi) in carefully purified and degassed solutions, irradiated by 5.90 eV photons.
Abstract: The field dependence of the relative decrease of fluorescence ΔF/F0 and of the photocurrent, i, is measured for dilute solutions of N,N,N′,N′‐tetramethylparaphenylenediamine (TMPD) in 2,2,4‐trimethylpentane (TMP) and tetramethylsilane (TMSi). In carefully purified and degassed solutions, irradiated by 5.90 eV photons, at 292 K, and E=45 kV cm−1, one obtains: ΔF/F0=3.9×10−2 in TMP and 11.8×10−2 in TMSi. The data are in good agreement with a model based on Onsager theory for electron escape. It is shown how the combined measurement of ΔF/F0 and i permits the determination of the free electron quantum yield at zero field, Φe0. For TMP:Φe0 =1.4×10−2 and for TMSi:Φe0=6.98×10−2. Finally it is shown that the field dependence of Φe, the free electron quantum yield at E, may be calculated from the experimental data.

31 citations

Journal ArticleDOI
TL;DR: In this article, the authors derived nonlinear wave equations describing the propagation of optical pulses of duration up to a period of electromagnetic oscillations in transparent media with uniaxial optical anisotropy.
Abstract: Nonlinear wave equations describing the propagation of optical pulses of duration up to a period of electromagnetic oscillations in transparent media with uniaxial optical anisotropy are derived on the basis of a quantum-mechanical model of material response. The electron and electron-vibrational nonlinearities, electron and ion dispersion, and diffraction are taken into account. It is shown that the inclusion of the electron response alone leads to a system of two constitutive equations for the ordinary and extraordinary polarization components. When a pulse propagates across the optical axis, this system is reduced to an inhomogeneous model of the Henon-Heiles type and, hence, generalizes the Lorentz classical electron model. In order to take into account stimulated Raman scattering (SRS) processes, an anisotropic analog of the Bloembergen-Shen quantum-mechanical model taking into account the population dynamics of SRS sublevels is obtained. The generation of an extraordinary wave video pulse with the help of the high-frequency ordinary component in the Zakharov-Benney resonance mode is investigated. Some analytic soliton-like solutions in the form of propagating bound states of ordinary and extraordinary video pulses corresponding to different birefringence modes are considered and their stability to self-focusing is analyzed.

30 citations

Journal ArticleDOI
TL;DR: In this paper, an experimental and theoretical study on the Faraday rotation in cadmium sulfide is presented, where the contribution of the free carriers is calculated from the experimental curves, and an electron effective mass of 0.20 ± 0.01 is obtained.
Abstract: An experimental and theoretical study on the Faraday rotation in cadmium sulfide is presented. The contribution of the free carriers is calculated from the experimental curves, and an electron effective mass of 0.20 ± 0.01 is obtained. A detailed description of the experimental arrangement is given, which allows a precision of ± 0.1 degrees.

30 citations

Journal ArticleDOI
TL;DR: In this article, the initiation and development of a breakdown of highly overvoltaged high-pressure (from 4 to 40 atm) gas gaps by voltage pulses having the risetime of 1 ns or shorter are studied experimentally and in theoretical terms.
Abstract: The initiation and the development of a breakdown of highly overvoltaged high-pressure (from 4 to 40 atm) gas gaps by voltage pulses having the risetime of 1 ns or shorter are studied experimentally and in theoretical terms. The study revealed that ionization processes leading to the breakdown start in the gas volume and not from the surface of the electrodes. The gap flashover is followed by ionization wave processes initiating in the gas volume and playing the decisive role at the first phase of the breakdown. The dynamics of the ionization waves strongly depends on the initial distribution of free electrons over the gas gap. The distribution of ionization waves is analysed when the initial electrons are distributed uniformly and nonuniformly over the gap. The calculation results are in qualitative agreement with the relevant experimental data. It is shown that the propagation of the ionization waves at the initial stage of subnanosecond pulsed electrical breakdown of gas leads to a redistribution of the electric field in the discharge gap and a region of a strong field, whose intensity is sufficient for the onset of emission processes and the generation of a short beam of fast electrons near the cathode, is formed at the cathode for a very short (up to 100 ps) time.

30 citations

Journal ArticleDOI
TL;DR: In this paper, the electronic stopping power of hydrogen and helium ions in Ag and Pt was determined, and the results were compatible with modeling the conduction band as a free electron gas with an energy-dependent effective number of electrons.
Abstract: In recent energy loss measurements, band structure effects in electronic stopping have been observed for materials with finite excitation thresholds, for example, noble metals such as Cu and Au. To further investigate the influence of the position of the $d$ band relative to the Fermi edge, electronic stopping of hydrogen and helium ions in Ag and Pt was determined. For Ag, the electronic stopping power exhibits a velocity dependence similar to Cu and Au. No particular effect due to the comparatively large $d$-band offset in Ag is found. In the case of Pt, the electronic stopping power is virtually velocity proportional for H${}^{+}$ ions and exhibits a distinct velocity dependence for He${}^{+}$ ions. For hydrogen the results are compatible with modeling the conduction band as a free electron gas with an energy-dependent effective number of electrons. For He${}^{+}$, however, the observed effects point towards an additional energy loss mechanism, e.g., by charge-exchange processes.

30 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202340
202290
2021132
2020122
2019114
2018112