Temat: 32.80.Fb - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Resonance Ionization Spectroscopy and its Application
Autorzy:: Kluge, H.-J.
Tematy:: 32.80.Fb; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1931508.pdf Link otwiera się w nowym oknie
Opis:: Resonance ionization spectroscopy and its combination with mass spectrometry offer very high sensitivity and selectivity. The application of several variants of resonance ionization mass spectroscopy to the study of nuclear ground state properties and trace analysis of radioactive isotopes in the environment is discussed as well as the inverse process, i.e. the laser induced recombination, of bare heavy ions stored at relativistic energies in storage rings.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Non-Perturbative Dynamics of Atoms in Strong Lrser Fields: Adiabatic Stability of Hydrogen Atom
Autorzy:: Faisal, F. H. M
Dimou, L.
Tematy:: 32.80.Fb
32.80.Wr; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1931518.pdf Link otwiera się w nowym oknie
Opis:: Recent investigations of laser-atom interaction at high intensities have led to the discovery of several unexpected phenomena, and their studies have deepened our understanding of non-perturbative dynamics of quantum systems subjected to unusually strong radiation fields. For the analysis and interpretation of these phenomena. We have developed an ab initio non-perturbative method, the Floquet close-coupling method, and applied it to analyse the highly non-perturbative problem of adiabatic stability of hydrogen atom. Ab initio rates of ionization as a function of the laser intensity for the excited circular states as well as related non-circular states are obtained. Our quantitatively accurate results clearly show that the predictions of the previous approximate theories such as the well-known "high-frequency" theory are qualitatively similar but differ quantitatively. The analysis of the dependence of adiabatic stability on the principal quantum number, the angular momentum, as well as on the magnetic quantum number for the Rydberg states are complemented by investigations of the behavior of the ground state for frequencies below the ionization threshold. In the latter situation we found the existence of stability windows within which the ionization probability decreases with increasing intensity but outside of which the atom becomes more unstable. It is shown here that the mechanism for the occurrence of stability windows is the self-tuned anti-resonance at specific intensities.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Photoionization of He - a Field Theoretic Approach
Autorzy:: Bhattacharyya, S.
Mitra, S.
Tematy:: 32.80.Cy
32.80.Fb; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2028891.pdf Link otwiera się w nowym oknie
Opis:: The present paper deals with the field theoretic study of single ionization cross-sectionsσ$\text{}_{ph}$ and σ$\text{}_{C}$ of helium due to photoelectric effect and the Compton scattering, respectively, by photons of energy lying between 0-12 keV. In this energy range,σ$\text{}_{ph}$ gradually decreases with energy whileσ$\text{}_{C}$ gradually increases. There is a crossover point around 6.5 keV where σ$\text{}_{ph}$=σ$\text{}_{C}$=10$\text{}^{-24}$ cm$\text{}^{2}$. Near about this crossover point σ$\text{}_{ph}$ andσ$\text{}_{C}$ curves are like mirror images. The ratio σ$\text{}_{C}$/σ$\text{}_{ph}$ lies between 0.3 to 1.5 in the energy range under consideration. The present results are compared with existing theoretical results.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Three-Particle Recombination at Low Temperature: a QED Approach
Autorzy:: Bhattacharyya, S.
Roy, A.
Tematy:: 32.80.Fb
33.55.Ad; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2027431.pdf Link otwiera się w nowym oknie
Opis:: A theoretical study of the three-body recombination of proton and electron in presence of a spectator electron with electronic beam at near-zero temperature is presented using field theory and invariant Lorentz gauge. Contributions from the Feynman diagrams of different orders give an insight into the physics of the phenomena. Recombination rate coefficient is obtained for low lying principal quantum number n=1 to 10. At a fixed ion beam temperature (300 K) recombination rate coefficient is found to increase in general with n, having a flat and a sharp peak at quantum states 3 and 5, respectively. In absence of any other theoretical and experimental results for low temperature formation of H-atom by three-body recombination at low lying quantum states, we have presented the theoretical results of Stevefelt and group for three-body recombination of deuteron with electron along with the present results. Three-body recombination of antihydrogen in antiproton-positron plasma is expected to yield similar result as that for three-body recombination of hydrogen formation in proton-electron plasma. The necessity for experimental investigation of low temperature three-body recombination at low quantum states is stressed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Transition Rate Dependence on the Non-Zero Initial Momentum in the ADK-Theory
Autorzy:: Ristić, V. M.
Miladinović, T. T.
Radulović, M. M.
Tematy:: 32.80.-t
32.80.Fb
32.80.Rm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2047850.pdf Link otwiera się w nowym oknie
Opis:: Tunneling regime, introduced by Keldysh, in the interaction of strong lasers with atoms has been now accepted as the reliable method for describing processes when low frequency lasers are involved. Yet it was always assumed that the ionized electrons are leaving the atom with zero initial momentum. Because we are interested in how non-zero momentum influences the transition probability of tunnel ionization, we obtained the exact expression for the momentum. Here the estimation of the transition probability with nonzero momentum included was conducted. Potassium atoms in the laser field whose intensity varied from 10$\text{}^{13}$ W/cm$\text{}^{2}$ to 10$\text{}^{14}$ W/cm$\text{}^{2}$ were studied. It seems that all energy of laser field is used for tunneling ionization process at the beginning of laser pulse - ionization probability is large. After that, with further action of laser pulse, ionization probability decreases, probably because part of laser pulse energy is used for increasing momentum of ejected electrons, leaving smaller amounts of light quanta available for ionization of remaining electrons. If laser pulse lasts long enough, then the amounts of light quanta available for ionization become larger, resulting in increase in ionization probability, now with greater starting energy of ejected electrons.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Calculating Ionization Transition Rate for Circularly Polarized Fields, Including Non-Zero Initial Momentum
Autorzy:: Ristić, V.
Miladinović, T.
Radulović, M.
Tematy:: 32.80.-t
32.80.Fb
32.80.Rm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1791204.pdf Link otwiera się w nowym oknie
Opis:: Potassium atoms in circularly polarized laser field whose intensity (I) varies from 2× $10^{12}$ W/$cm^2$ to 2.5× $10^{14}$ W/$cm^2$ were studied. In the case when there is zero initial momentum, transition rate (that depends only on I) exhibits standard behaviour: as I increases, so thus the rate, until it reaches its maximum value at 1.1× $10^{14}$ W/$cm^2$; after that, rate diminishes as I increases. In the case of non-zero initial momentum, transition rate (that now depends on I but additionally on initial momentum, too) exhibits following behaviour: dependence of the rate on I follows standard pattern, it rises with increase of I until it reaches its maximum, and then diminishes. But with increase of momentum, ionization rate gradually diminishes.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Laser-Matter Interaction with Intense Short Laser Pulses
Autorzy:: Lompré, L. A.
Tematy:: 32.80.Fb
32.80.Rm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1931493.pdf Link otwiera się w nowym oknie
Opis:: Laser-matter interaction in rare gases (He, Ne, Ar and Xe) has been investigated using a 1 ps Nd-glass laser pulse at 1053 nm with intensities between 10$\text{}^{13}$ to 10$\text{}^{18}$ W/cm$\text{}^{2}$. Three aspects of the interaction have been studied: the creation of multiply charged ions, the energy of the ejected electron and the propagation in an underdense plasma. At the maximum laser intensity, all electrons of the outer shell are removed, except in Ne for which charge states up to 7+ are observed. Comparison of experimental data with Ammosov et al. tunneling model shows a very good agreement, indicating that ionization with a 1 ps pulse in the near infrared light mainly occurs in tunneling regime. Electrons created in a low-density medium with energies up to 5 keV have been detected. These energies are far above the energy acquired during the ionization process, indicating that at high laser intensities electron energy is governed by ponderomotive force. Finally, the study of the propagation of an intense laser pulse in an underdense plasma shows that it is not possible to obtain simultaneously high laser intensity (10$\text{}^{17}$-10$\text{}^{18}$ W/cm$\text{}^{2}$) and high electron density (10$\text{}^{19}$-10$\text{}^{20}$ cm$\text{}^{-3}$). Best conditions for solving this problem will be discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Strong-Field Phenomena in Atoms - Quasiclassical Approach
Autorzy:: Fedorov, M. V.
Tematy:: 32.80.Fb
32.80.Rm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1931525.pdf Link otwiera się w nowym oknie
Opis:: A quasiclassical (WKB) approach is used to construct a theory of atomic transitions induced by a strong light field. This approach is used to find the "Coulomb-Volkov" solutions of the Schrödinger equation in which both the Coulomb and light fields are taken into account. These solutions are shown to be applicable in a region of low light frequencies, low electron energies and angular momenta. The found solutions are used to describe two kinds of processes: strong-field photoionization from highly excited (Rydberg) atomic levels, and field-assisted electron-ion scattering. In the photoionization problem the strong-field complex quasi-energies of an atom are found. A problem of the strong-field stabilization of an atom, as well as the expected behavior of the ionization time in its dependence on the light field strength are discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: The Initial-value Problem in the Quasi-classical Theory of Strong-field Photoionization of Rydberg Atoms
Autorzy:: Tikhonova, O. V.
Fedorov, M. V.
Tematy:: 32.80.Fb
32.80.Rm; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1968511.pdf Link otwiera się w nowym oknie
Opis:: Photoionization of Rydberg atoms is considered in the quasi-classical (WKB) approach. The total nonlinear strong-field ionization rate is found and investigated. The time of ionization, as a function of a growing field-strength amplitude, is shown to approach asymptotically the Kepler period t$\text{}_{k}$. Interference stabilization of Rydberg atoms is confirmed to exist in the case of short pulses (shorter than the Kepler period).
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Influence of Ponderomotive Potential and NonZero Initial Momentum of Ejected Electron on Transition Rate in Multiphoton Ionization
Autorzy:: Miladinović, T.
Petrović, V.
Ristić, V.
Tematy:: 32.80.-t
32.80.Fb
32.80.Wr; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1399265.pdf Link otwiera się w nowym oknie
Opis:: The multiphoton ionization of neutral atoms irradiated by photons is an interesting topic for experimental and also theoretical examination. We study the influence of ponderomotive potential and non-zero initial momentum of ejected electrons on transition rate, and also on the generalized cross-section in the case of a multiphoton ionization process. Also, we study how the transition rate depends on the number of absorbed photons.
Dostawca treści:: Biblioteka Nauki

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