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H. G. Berry

Bio: H. G. Berry is an academic researcher from University of Notre Dame. The author has contributed to research in topics: Excited state & Ion. The author has an hindex of 32, co-authored 166 publications receiving 3757 citations. Previous affiliations of H. G. Berry include University of Lyon & University of Arizona.


Papers
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Journal ArticleDOI
TL;DR: A measuring system for determining the state of polarization of a beam of light in terms of its Stokes parameters which can be fully automated incorporates a monochromator and single photon counting detection and can be applied over a large wavelength range for very weak optical signals.
Abstract: We describe a measuring system for determining the state of polarization of a beam of light in terms of its Stokes parameters. The technique which can be fully automated incorporates a monochromator and single photon counting detection and can thus be applied over a large wavelength range for very weak optical signals. Fourier transformation of the data by an on-line minicomputer allows immediate calculation of the Stokes parameters. We discuss special applications to light emitted from excited atomic systems with and without cylindrical symmetry.

293 citations

Journal ArticleDOI
TL;DR: The measurement techniques of beam-foil spectroscopy are reviewed in this paper, which includes the study of wavelengths of heavy ions with low and high charge states at visible, UV and X-ray wavelengths from normal excited states, multiply excited states and high-n Rydberg levels.
Abstract: The measurement techniques of beam-foil spectroscopy are reviewed. These comprise the study of wavelengths of heavy ions with low and high charge states at visible, UV and X-ray wavelengths from normal excited states, multiply excited states and high-n Rydberg levels; the measurements of mean lifetimes above 10-12 s and metastable states up to 100 ns; high-resolution Auger electron measurements; and the application of atomic alignment and orientation by both perpendicular and tilted foils to measurements of atomic structures and analysis of the beam-foil excitation process. A theoretical description of the emission of light from anisotropically excited systems is included. Associated techniques of time-resolved spectroscopy are compared.

210 citations

Journal ArticleDOI
TL;DR: The mean life of the 3d 2 D doublet in SiII has been determined to be 047 ± 003 ns by a technique which utilizes arbitrarily normalized decay curves of all direct cascades in the analysis of the decay curve of the measured level, and thus exactly accounts for cascade effects as mentioned in this paper.

155 citations

Journal ArticleDOI
TL;DR: A theoretical model is presented indicating that the total interaction cross section contains roughly equal contributions from (a) excitation of the giant plasmon resonance, and (b) large-energy-transfer processes that lead to multiple fragmentation of the molecule.
Abstract: Ionization and multifragmentation have been observed in C[sub 60] molecules bombarded by Xe[sup 35+] and Xe[sup 18+] ions with energies in the range 420--625 MeV. The c.m. energies exceeded those used in previous studies by several orders of magnitude. We present the observed mass distribution of positively charged fragments together with a theoretical model indicating that the total interaction cross section contains roughly equal contributions from (a) excitation of the giant plasmon resonance, and (b) large-energy-transfer processes that lead to multiple fragmentation of the molecule.

98 citations


Cited by
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Journal ArticleDOI
TL;DR: In this article, electron correlations in a direct nonlinear process of inner-shell excitation were found to be important in multielectron processes, leading to evidence for a role of electron correlation in the nonlinear processes of inner shell excitation.
Abstract: Measurements of the vacuum-ultraviolet (<80-nm) radiation produced by intense ultraviolet (248-nm) irradiation (1015–1016 W/cm2) of rare gases have revealed the copious presence of both harmonic radiation and fluorescence from excited levels. The highest harmonic observed was the seventeenth (14.6 nm) in Ne, the shortest wavelength ever produced by that means. Strong fluorescence was seen from ions of Ar, Kr, and Xe, with the shortest wavelengths observed being below 12 nm. Furthermore, radiation from inner-shell excited configurations in Xe, specifically the 4d95s5p → 4d105s manifold of Xe7+ at ~17.7 nm, was detected. These experimental findings, in alliance with other studies concerning multielectron processes, give evidence for a role of electron correlations in a direct nonlinear process of inner-shell excitation.

1,409 citations

Journal ArticleDOI
TL;DR: In this article, the authors present a comprehensive set of FDCSs for single ionization of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies.
Abstract: Recoil-ion and electron momentum spectroscopy is a rapidly developing technique that allows one to measure the vector momenta of several ions and electrons resulting from atomic or molecular fragmentation. In a unique combination, large solid angles close to 4π and superior momentum resolutions around a few per cent of an atomic unit (a.u.) are typically reached in state-of-the art machines, so-called reaction-microscopes. Evolving from recoil-ion and cold target recoil-ion momentum spectroscopy (COLTRIMS), reaction-microscopes—the `bubble chambers of atomic physics'—mark the decisive step forward to investigate many-particle quantum-dynamics occurring when atomic and molecular systems or even surfaces and solids are exposed to time-dependent external electromagnetic fields. This paper concentrates on just these latest technical developments and on at least four new classes of fragmentation experiments that have emerged within about the last five years. First, multi-dimensional images in momentum space brought unprecedented information on the dynamics of single-photon induced fragmentation of fixed-in-space molecules and on their structure. Second, a break-through in the investigation of high-intensity short-pulse laser induced fragmentation of atoms and molecules has been achieved by using reaction-microscopes. Third, for electron and ion-impact, the investigation of two-electron reactions has matured to a state such that the first fully differential cross sections (FDCSs) are reported. Fourth, comprehensive sets of FDCSs for single ionization of atoms by ion-impact, the most basic atomic fragmentation reaction, brought new insight, a couple of surprises and unexpected challenges to theory at keV to GeV collision energies. In addition, a brief summary on the kinematics is provided at the beginning. Finally, the rich future potential of the method is briefly envisaged.

1,375 citations

Journal ArticleDOI
17 Jan 2014-Science
TL;DR: Spin precession measurements in the polar molecule thorium monoxide indicate a nearly spherical charge distribution of an electron, which constrains T-violating physics at the TeV energy scale.
Abstract: The Standard Model of particle physics is known to be incomplete. Extensions to the Standard Model, such as weak-scale supersymmetry, posit the existence of new particles and interactions that are asymmetric under time reversal (T) and nearly always predict a small yet potentially measurable electron electric dipole moment (EDM), d(e), in the range of 10(-27) to 10(-30) e·cm. The EDM is an asymmetric charge distribution along the electron spin (S(→)) that is also asymmetric under T. Using the polar molecule thorium monoxide, we measured d(e) = (-2.1 ± 3.7stat ± 2.5syst) × 10(-29) e·cm. This corresponds to an upper limit of |d(e)| < 8.7 × 10(-29) e·cm with 90% confidence, an order of magnitude improvement in sensitivity relative to the previous best limit. Our result constrains T-violating physics at the TeV energy scale.

1,040 citations

Journal ArticleDOI
TL;DR: The cold target recoil ion momentum spectroscopy (COLTRIMS) is a momentum space imaging technique for the investigation of the dynamics of ionizing ion, electron or photon impact reactions with atoms or molecules as mentioned in this paper.

985 citations

Journal ArticleDOI
TL;DR: In this paper, a list of atomic data for the lighter elements from hydrogen to gallium is presented, with a focus on resonance lines, i.e., lines whose lower level is the ground state, or an excited fine-structure state of the ground term, and restricted to wavelengths longward of the H I Lyman limit at 911.753?.
Abstract: This compilation revises the 1991 listing of atomic data for the lighter elements from hydrogen to gallium. The tabulation emphasizes resonance lines, i.e., lines whose lower level is the ground state, or an excited fine-structure state of the ground term, and is restricted to wavelengths longward of the H I Lyman limit at 911.753 ?. All but the very weakest known and predicted electric-dipole transitions are included, but no forbidden lines. This paper has attempted to review all data published by the end of 2002.?????The tables contain the best data available to the author on ionization potentials, level designations, vacuum and air wavelengths, lower and upper energy levels, statistical weights, transition probabilities, natural damping constants (reciprocal lifetimes), oscillator strengths, and the often used combinations of log gf and log ?f. All ion stages with relevant classified lines are included. Individual components resulting from isotope shift and hyperfine structure are listed explicitly for certain species. The accompanying text provides references, explanations for the critical selection of data, and notes indicating where new measurements or calculations are needed.?????This compilation should be particularly useful in the analysis of interstellar and quasar absorption lines and other astrophysical sites where the density of particles and radiation is low enough to excite only the lowest atomic levels. The data also are relevant to the study of stellar atmospheres, and gaseous nebulae.?????An Appendix summarizes new data relevant to the similar compilation in Paper II for the elements germanium to uranium.

806 citations