963 resultados para PHOTOIONIZATION CODE


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Setting out the responsibilities of educational institutions to ensure that learning analytics is carried out responsibly, appropriately and effectively.

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Raquel Merino Álvarez, José Miguel Santamaría, Eterio Pajares (eds.)

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La pêche, y compris l'aquaculture, apporte une contribution fondamentale à l'alimentation, à l'emploi, aux loisirs, au commerce et au bien-être économique des populations du monde entier, qu'il s'agisse des générations présentes ou futures, et devrait, par conséquent, être conduite de manière responsable. Le présent Code définit des principes et des normes internationales de comportement pour garantir des pratiques responsables en vue d'assurer effectivement la conservation, la gestion et le développement des ressources bioaquatiques, dans le respect des écosystèmes et de la biodiversité. Le Code reconnaît l'importance nutritionnelle, économique, sociale, environnementale et culturelle de la pêche et les intérêts de tous ceux qui sont concernés par ce secteur. Le Code prend en considération les caractéristiques biologiques des ressources et de leur environnement, ainsi que les intérêts des consommateurs et autres utilisateurs. Les Etats et tous ceux impliqués dans le secteur de la pêche sont encouragés à appliquer ce Code de manière effective. (PDF contains 53 pages)

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(PDF contains 17 pages)

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(PDF contains 19 pages)

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Attosecond-pulse extreme-ultraviolet (XUV) photoionization in a two-color laser field is investigated. Attosecond pulse trains with different numbers of pulses are examined, and their strong dependence on photoelectronic spectra is found. Single-color driving-laser-field-assisted attosecond XUV photoionization cannot determine the number of attosecond pulses from the photoelectronic energy spectrum that are detected orthogonally to the beam direction and the electric field vector of the linearly polarized laser field. A two-color-field-assisted XUV photoionization scheme is proposed for directly determining the number of attosecond pulses from a spectrum detected orthogonally. (C) 2005 Optical Society of America.

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By means of the numerical solution of time-dependant Schrodinger equation, we verify a scaling law of photoionization in ultrashort pulses. We find that for a given carrier-envelope phase and duration of the pulse, identical photoionizations are obtained provided that when the central frequency of the pulse is enlarged by k times, the atomic binding potential is enlarged by k times, and the laser intensity is enlarged by k(3) times. The scaling law allows us to reach a significant control over direction of photoemission and offers exciting prospects of reaching similar physical processes in different interacting systems which constitutes a novel kind of coherent control.

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Using an unperturbed scattering theory, the characteristics of H atom photoionization are studied respectively by a linearly- and by a circularly- polarized one-cycle laser pulse sequence. The asymmetry for photoelectrons in two directions opposite to each other is investigated. It is found that the asymmetry degree varies with the carrier-envelope (CE) phase, laser intensity, as well as the kinetic energy of photoelectrons. For the linear polarization, the maximal ionization rate varies with the CE phase, and the asymmetry degree varies with the CE phase in a sine-like pattern. For the circular polarization, the maximal ionization rate keeps constant for various CE phases, but the variation of asymmetry degree is still in a sine-like pattern.