Topic
Photoionization
About: Photoionization is a research topic. Over the lifetime, 19129 publications have been published within this topic receiving 451875 citations. The topic is also known as: photo-ionization.
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TL;DR: The production of He[sup +] and He[Sup 2+] by a 160 fs, 780 nm laser has been measured over an unprecedented 12 orders of magnitude in counting range and the NS yield is found to scale with the ac-tunneling rate for the neutral, even when tunneling is not the dominant ionization pathway.
Abstract: The production of ${\mathrm{He}}^{+}$ and ${\mathrm{He}}^{2+}$ by a 160 fs, 780 nm laser has been measured over an unprecedented 12 orders of magnitude in counting range. Enhanced double electron emission, called nonsequential (NS) ionization, was observed over an intensity range where the single ionization dynamics is evolving from multiphoton to pure tunneling. The NS yield is found to scale with the ac-tunneling rate for the neutral, even when tunneling is not the dominant ionization pathway. A rescattering mechanism fails to predict the observed NS threshold or magnitude.
711 citations
01 Jan 1978
TL;DR: Theory of photoemission: Independent particle model and the calculation of photoionization cross sections: An atomic view as discussed by the authors, and manyelectron and final-state effects: Beyond the one-electron picture.
Abstract: Theory of photoemission: Independent particle model.- The calculation of photoionization cross sections: An atomic view.- Many-electron and final-state effects: Beyond the one-electron picture.- Fermi surface excitations in X-ray photoemission line shapes from metals.- Angular dependent photoemission.
704 citations
TL;DR: The technique relies on establishing an absolute reference point in the laboratory frame by elliptical polarization of the laser pulse, from which field-induced momentum shifts of the emergent electron can be assigned to a temporal delay on the basis of the known oscillation of the field vector.
Abstract: It is well established that electrons can escape from atoms through tunneling under the influence of strong laser fields, but the timing of the process has been controversial and far too rapid to probe in detail. We used attosecond angular streaking to place an upper limit of 34 attoseconds and an intensity-averaged upper limit of 12 attoseconds on the tunneling delay time in strong field ionization of a helium atom. The ionization field derives from 5.5-femtosecond-long near-infrared laser pulses with peak intensities ranging from 2.3 × 1014 to 3.5 × 1014 watts per square centimeter (corresponding to a Keldysh parameter variation from 1.45 to 1.17, associated with the onset of efficient tunneling). The technique relies on establishing an absolute reference point in the laboratory frame by elliptical polarization of the laser pulse, from which field-induced momentum shifts of the emergent electron can be assigned to a temporal delay on the basis of the known oscillation of the field vector.
644 citations
TL;DR: In this article, a critical review of the existing data on ionization and dielectronic recombination and present new computations of radiative recombination rate coefficients of Fe(+14) through Fe(−25) using the photoionization cross sections of Clark et al.
Abstract: In the past few years important progress has been made on the knowledge of ionization and recombination rates of iron, an astrophysically abundant heavy element and a major impurity in laboratory fusion devices. We make a critical review of the existing data on ionization and dielectronic recombination and present new computations of radiative recombination rate coefficients of Fe(+14) through Fe(+25) using the photoionization cross sections of Clark et al. (1986). We provide analytical fits to the recommended data (direct ionization and excitation-autoionization cross sections; radiative and dielectronic recombination rate coefficients). Finally we determine the iron ionic fractions at ionization equilibrium and compare them with previous computations as well as with observational data.
633 citations