Showing papers on "Photoexcitation published in 1976"
TL;DR: In this article, the photoexcitation matrix element is shown to depend on the degree of localization of the final-state wavefunction at the surface, and spectral regimes and experimental conditions are defined which are expected to give enhanced surface sensitivity.
Abstract: Photoemission energy distribution spectra of clean metal and semiconductor surfaces are interpreted in terms of emission from electronic states characteristic of both the surface and 'infinite' bulk crystal. The photoexcitation matrix element is shown to depend on the degree of localization of the final-state wavefunction at the surface. Using the concept that the emitted electron is represented by an incoming plane wave, spectral regimes and experimental conditions are defined which are expected to give enhanced surface sensitivity. Experimental results are presented to illustrate the nature of the surface and volume photoelectric effect in nearly-free-electron metals, semiconductors, and transition metals.
93 citations
TL;DR: In this article, the relativistic corrections of order (quark mass)−2 to the baryon resonance photoexcitation amplitudes in the harmonic-oscillator quark model were calculated.
36 citations
34 citations
TL;DR: In this article, a scheme for population inversion in the soft x-ray (≳100 A) region, where the upper laser level is photoexcited by resonant line radiation from an identical or different ion species, is proposed.
Abstract: A scheme for population inversion in the soft x‐ray (≳100 A) region, where the upper laser level is photoexcited by resonant line radiation from an identical or different ion species, is proposed. Ion pairs that may be used in this scheme are presented. Applying the results obtained for a general case to the Mg XII ions pumped by C VI ions, it is shown that gains in excess of 100 cm−1 are possible for the 4→3 transition at ∼130 A in typical laser‐produced plasmas.
27 citations
TL;DR: In this article, an investigation of the energy transfer between the Gd3+ and Mn2+ ions in CaF2Gd, Mn crystals under photoexcitation is made.
Abstract: An investigation is made of the energy transfer between the Gd3+ and Mn2+ ions in CaF2Gd, Mn crystals under photoexcitation. The studies performed at varied concentrations and with measurement of the lifetimes of the excited states reveal that the process is intracentric and that only the noncubic luminescent centres of gadolinium seem to be involved in the energy transfer from the Gd3+ ions to the Mn2+ ions.
[Russian Text Ignored].
14 citations
11 citations
10 citations
Book•
01 Jan 1976
TL;DR: In this paper, a new experimental study of multiple ionization in Noble Gases by Electron and Photon impact is presented, which investigates correlation effects in X-ray emission spectroscopy and Auger Electron Spectroscopy.
Abstract: to the School Program.- Correlations of Excited Electrons.- Photoionization Processes.- The Single Electron Model in Photoionization.- Shake Theory of Multiple Photoexcitation Processes.- The Random Phase Approximation with Exchange.- Photoionization Cross Sections and Auger Rates Calculated by Many-Body Perturbation Theory.- Photoabsorption Spectroscopy of Atoms in the Extreme Ultraviolet (XUV) Spectral Region.- Photoelectron Spectrometry: Experiments with Atoms.- Charged Particle Collisions.- Theoretical Aspects of Electron Correlations in Electron Collisions.- High-Energy Electron Experiments.- Some Experiments on Collisions between Electrons and Atoms or Ions which Investigate Correlation Effects.- The Quasi-Molecular Model in Heavy Particle Collisions.- Nuclear Excitation.- Ionization by Nuclear Transitions.- Inner-Shell Rearrangement.- Theory of Atomic Decay following Inner-Shell Ionization.- Correlation Effects in X-Ray Emission Spectroscopy.- Correlation Effects in Auger Electron Spectroscopy.- Ions, Molecules, Solids.- Some Aspects of Inner Shell Phenomena for the Ions in a Plasma.- Multiple Excitation in Free Molecules.- High Energy Excitations in Molecules and Solids.- Seminars.- Relativistic Effects in Atomic Structure Calculation: An Introduction.- A New Experimental Study of Multiple Ionization in Noble Gases by Electron and Photon Impact.- A Primer on Photoelectron Angular Distributions.- The Quantum Defect Theory Approach.- The Close-Coupling Methods Applied to Photoionization of Neutral Atoms and Positive Ions.- Future Experimental Problems in Photoionization.- Concluding Remarks.- Author Index.
5 citations
01 Jan 1976
TL;DR: In this article, photo ionization processes in which the ionization of an electron is accompanied by direct excitation or ionisation of additional electrons are considered, and indirect processes of auto ionization like the Auger effect are discussed.
Abstract: In this lecture we consider photo ionization processes in which the ionization of an electron is accompanied by direct excitation or ionization of additional electrons The indirect processes of auto ionization like the Auger effect which beco me possible when the photons have enough energy to produce singly-ionized inner-shell hole states above the double ionization threshold are discussed in the second lecture
4 citations
TL;DR: In this paper, the wave vector dependence of the two photon absorption by a polymer is analyzed and it is shown that there is a geometric equivalent to the removal of two photon Doppler broadening in dilute gases.
4 citations
TL;DR: In this article, the form factor for the virtual excitation of the core is expressed in terms of the form factors for elastic scattering from the core nucleus by utilizing sum rules developed by Fallieros, Noble, and Ui et al.
TL;DR: In this article, a significant increase of the recombination barrier φ rec takes place with an increase of photoexcitation level in a highly compensated semiconductor with large-scale fluctuations of electrostatic potential, which makes it possible to increase the photosensitivity of the material by several orders of magnitude at the additional illumination use.
01 Jun 1976
TL;DR: In this paper, the results of experiments to study the behavior of superconductors under light illumination were discussed, and the authors proposed a method to study superconductivity in light illumination.
Abstract: Dissertation discussing the results of experiments to study the behavior of superconductors under light illumination.
01 Jan 1976
TL;DR: In this paper, a study of the color centers formed in ruby by high-power optical and γ -ray irradiation was made, which made it possible to give a qualitative interpretation of the Cr3+ spectrum in the vacuum ultraviolet region, refine the mechanism of quantum losses in photoexcitation of ruby, and propose a model of the energy band structure.
Abstract: Investigation was made of the spectra of Cr3+ in A12O3 in the 900–8000 A range. A study was made of the nature of the color centers formed in ruby by high-power optical and γ -ray irradiation. The influence of an anisotropic perturbation by an external electric field on the probability of some transitions in the Cr3+ ion was determined. The results obtained made it possible to give a qualitative interpretation of the Cr3+ spectrum in the vacuum ultraviolet region, refine the mechanism of quantum losses in the photoexcitation of ruby, and propose a model of the energy band structure. The influence of the color centers on the Cr3+ spectrum and on the laser characteristics was considered.
02 Aug 1976
TL;DR: In this paper, the initial species, partitioning of energy, electron flux spectra and derived quantities resulting from UV photon and electron absorption by atmospheric species are calculated for the altitude range 60 to 500 km and for photon energies between 10 and 300 eV and 14 and 900 eV, respectively.
Abstract: : The initial species, partitioning of energy, electron flux spectra and derived quantities resulting from UV photon and electron absorption by atmospheric species are calculated for the altitude range 60 to 500 km and for photon and electron energies between 10 and 300 eV and 14 and 900 eV, respectively. Cross-section curves for electron impact excitation of nitrogen to predissociating states are derived. (Author)