scispace - formally typeset
Search or ask a question
Topic

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.


Papers
More filters
Journal ArticleDOI
TL;DR: A theoretical approach to calculate differential and total ionization cross sections of polyatomic molecules by fast electron impact using the distorted wave Born approximation without exchange by employing the independent electron model.
Abstract: In this paper, we present a theoretical approach to calculate differential and total ionization cross sections of polyatomic molecules by fast electron impact. More exactly, we have studied the ionization of ammonia (NH3) and methane (CH4) molecules, and previous results concerning the H2O molecule ionization are reported for comparison. The calculations are performed in the distorted wave Born approximation without exchange by employing the independent electron model. The molecular target wave functions are described by linear combinations of atomic orbitals. To describe the interaction between the inactive target electrons and the slow ejected electron, we have introduced a distortion via an effective potential calculated for each molecular orbital. The present theoretical calculations agree well with a large set of existing experimental data in terms of multiple differential and total cross sections.

31 citations

Journal ArticleDOI
TL;DR: The band structure of lead sulphide has been investigated using angle-resolved photoemission, with synchrotron radiation in the photon energy range 25-95 eV as the excitation source as mentioned in this paper.
Abstract: The band structure of lead sulphide has been investigated using angle-resolved photoemission, with synchrotron radiation in the photon energy range 25-95 eV as the excitation source. Many spectral features originate from direct transitions, while others are due to 'density of state' features, i.e. they arise from electrons scattered into the observation direction. Good agreement was found between the experimental spectra and transitions expected on the basis of the calculated linearized muffin-tin-orbital (LMTO) band structure and free electron final states. Partial yield spectra at the Pb O4,5 edge are also reported, from which it is concluded that the exciton energy in lead chalcogenides is not anomalously large, in contradiction to previous work.

31 citations

Journal ArticleDOI
TL;DR: Optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density are detected and can be isolated from concomitant optical responses by using a noncollinear pump-probe setup.
Abstract: We have experimentally detected optical harmonics that are generated due to a tunneling-ionization-induced modulation of the electron density. The optical signature of electron tunneling can be isolated from concomitant optical responses by using a noncollinear pump-probe setup. Whereas previously demonstrated tools for attosecond metrology of gases, plasmas, and surfaces rely on direct detection of charged particles, detection of the background-free time-resolved optical signal, which uniquely originates from electron tunneling, offers an interesting alternative that is especially suited for systems in which free electrons cannot be directly measured.

31 citations

Journal ArticleDOI
TL;DR: In this paper, the coupling of excitons associated with higher subbands and free electrons in the lowest subband was investigated using a two-band Mahan-Nozi\´eres--De Dominicis Hamiltonian.
Abstract: In asymmetric quantum wells, optical transitions couple a hole state with several conduction-band states. The coupling of excitons associated with higher subbands and free electrons in the lowest subband are investigated using a two-band Mahan--Nozi\`eres--De Dominicis Hamiltonian. The emission spectrum for carriers in the lowest subband shows a very weak Fermi edge singularity at the Fermi level. When the Fermi level approaches the second subband, coupling of excitons with excitations of the Fermi sea leads to a large enhancement of the emission spectrum at the Fermi level.

31 citations

Journal ArticleDOI
TL;DR: It is demonstrated that oxygen vacancies and titanium interstitials act as shallow donors, and can form at substantial concentrations, giving rise to free electrons with carrier densities from 1011 to 1019 cm-3 under oxygen-rich and oxygen-poor conditions, respectively.
Abstract: The energetics and electronic structures of native defects in anatase TiO2 are comprehensively studied using hybrid density functional calculations. We demonstrate that oxygen vacancies (VO) and titanium interstitials (Tii) act as shallow donors, and can form at substantial concentrations, giving rise to free electrons with carrier densities from 1011 to 1019 cm-3 under oxygen-rich and oxygen-poor conditions, respectively. The titanium vacancies (VTi), identified as deep acceptors and induced hole carriers, are incapable of fully compensating for the free electrons originating from the donor-type defects at any oxygen chemical potential. Even under extreme oxygen-rich conditions, the Fermi level, which is determined from the charge neutrality condition among charge defects, electron and hole carriers, is located 2.34 eV above the valence band maximum, indicating that p-type conductivity can never be realized under any growth conditions without external doping. This is consistent with common observations of intrinsic n-type conductivity of TiO2. At a typical annealing temperature and under a typical oxygen partial pressure, the carrier concentration is found to be approximately 5 × 1013 cm-3.

31 citations


Network Information
Related Topics (5)
Electron
111.1K papers, 2.1M citations
95% related
Excited state
102.2K papers, 2.2M citations
91% related
Band gap
86.8K papers, 2.2M citations
90% related
Scattering
152.3K papers, 3M citations
89% related
Magnetic field
167.5K papers, 2.3M citations
89% related
Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202340
202290
2021132
2020122
2019114
2018112