Search

The results of studying the interaction H atoms with ZnS–Tm3+ surface using the phenomena of heterogeneous chemiluminescence (HCL) are presented. HCL is luminescence excited in the strongly exothermic interaction acts of hydrogen atoms on the surface. The kinetic and nonstationary characteristics of luminescence are studied in depending on the excitation conditions, which serve as light indicators of physicochemical processes, occurring on the surface. The interaction parameters of hydrogen atoms with the surface of zinc sulphide: cross-sections, frequency factors, activation energies based on kinetic and non-stationary characteristics of HCL are determined. • Features of the heterogeneous luminescence spectra in the first atomic layer. • Direct energy conversion into radiation at the hydrogen interaction with phosphor. • Non-stationary luminescent methods for studying of the atoms–surface interaction. • A theoretical model for explaining the experimental regularities developed. [ABSTRACT FROM AUTHOR]

The static and dynamic aspects of the Jahn-Teller (JT) interactions in the 3p(E′) and 3d(E″) Rydberg electronic states of H3 are analyzed theoretically. The static aspects are discussed based on recent ab initio quantum chemistry results, and the dynamic aspects are examined in terms of the vibronic spectra and nonradiative decay behavior of these states. The adiabatic potential-energy surfaces of these degenerate electronic states are derived from extensive ab initio calculations. The calculated adiabatic potential-energy surfaces are diabatized following our earlier study on this system in its 2p(E′) ground electronic state. The nuclear dynamics on the resulting conically intersecting manifold of electronic states is studied by a time-dependent wave-packet approach. Calculations are performed both for the uncoupled and coupled state situations in order to understand the importance of nonadiabatic interactions due to the JT conical intersections in these excited Rydberg electronic states. [ABSTRACT FROM AUTHOR]

We present single-photon spectroscopy in molecular hydrogen starting from the metastable c3Πu- state to a number of triplet nd-Rydberg states (v=0–4, n=12–20). Using fast beam spectroscopy both the autoionization channel and the predissociation channel are quantified, field free, as well as with small electric fields. Coupling with the i3Πg state is assumed to be responsible for field-free predissociation of the v=0 Rydberg levels. The stronger observed predissociation channel of the v=1 Rydberg levels is due to the nonadiabatic interaction with the h3Σg+ state in combination with l mixing due to an external electric field. No direct evidence is found for possible electric field induced predissociation of the gerade Rydberg states by low lying ungerade states. The competition between autoionization and predissociation is discussed in terms of possible consequences for dissociative recombination involving low energy electron collisions with the H2+ molecular ion. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The shape of atomic spectral lines in plasmas contains information on the plasma parameters, and can be used as a diagnostic tool. Under specific conditions, the plasma located at the edge of tokamaks has parameters similar to those in magnetic white dwarf stellar atmospheres, which suggests that the same line shape models can be used. A problem common to tokamak and magnetic white dwarfs concerns the modeling of Stark broadening of hydrogen lines in the presence of an external magnetic field and the related Zeeman effect. In this work, we focus on a selection of issues relevant to Stark broadening in magnetized hydrogen plasmas. Various line shape models are presented and discussed through applications to ideal cases. [ABSTRACT FROM AUTHOR]

Eight doubly excited 1 , 3 P ° resonances in He-like systems below the N = 3 hydrogenic threshold are investigated in the framework of Screening Constant by Unit Nuclear Charge (SCUNC) formalism. The Rydberg series investigated are labelled in the ( K , T , A ) classification scheme. Accurate data are tabulated for the entire He-isoelectronic sequence up to Z = 40 with 3 ≤ n ≤ 9 , n the principal quantum number of the outer electron. [ABSTRACT FROM AUTHOR]

Abstract: A collisional-radiative model for hydrogen atom, coupled self-consistently with the Boltzmann equation for free electrons, has been applied to model a shock tube. The kinetic model has been completed considering atom–atom collisions and the vibrational kinetics of the ground state of hydrogen molecules. The atomic level kinetics has been also coupled with a radiative transport equation to determine the effective adsorption and emission coefficients and non-local energy transfer. [Copyright &y& Elsevier]

We present a procedure to make direct diagnostics of the physical conditions of the regions of formation of the atomic spectral lines in stellar atmospheres using the atomic line widths at half maximum and the number of lines visible of a given atomic series in the observed stellar spectra. This is accomplished using the theoretical widths at half maximum of the atomic lines induced by the broadening produced by thermal energy fluctuations and considering the maximum number of levels that exist in those atoms under the physical conditions of the given system. The procedure is easy to use in any application. As an example we apply the procedure to the observed Lyman lines of hydrogen in the ultraviolet of some stars. [ABSTRACT FROM AUTHOR]

We construct a Dirac equation in κ-Minkowski spacetime and analyze its implications. This κ-deformed Dirac equation is expanded as a power series involving derivatives with respect to commutative coordinates and the deformation parameter, a. We show that the κ-deformation breaks the charge conjugation invariance but preserves parity and time reversal. We then study how the hydrogen atom spectrum is modified due to the κ-deformation, applying perturbation theory. Using this, we obtain bounds on the deformation parameter a, which are a few orders higher than the Planck length. We also show that the effects of deformation on the spectrum are distinct from that of Moyal deformation and generalized uncertainty principle. [ABSTRACT FROM AUTHOR]

The effect of pressure on the conductivity of molecular liquids (hydrogen, oxygen, and nitrogen) and alkali metals (cesium and rubidium) in the region of the experimentally observed dielectric-metal transition is investigated. It is shown that capture of free electrons by atoms or molecules (resulting in the formation of negative ions) is advantageous from the point of view of energy in liquids under moderately high pressures and temperatures. In spite of the fact that the ionization potential increases with density, the energy of an electron transition to the level of the negative ion decreases and, hence, the forbidden gap also decreases. For high densities, the level of negative ions is broadened and transformed into the conduction band. It is assumed that the exponential dependence of conductivity on density and temperature in the transition region is associated with transfer of quasi-free electrons located at the level of atomic negative ions. The spectrum of negative ions of hydrogen, oxygen, and cesium in the strongly compressed state is determined, and the forbidden gap calculated for these substances is found to be in good agreement with the results obtained for hydrogen and oxygen in single shock-wave experiments. [ABSTRACT FROM AUTHOR]

Corrections of order α 5 and α 6 are calculated for muonic hydrogen in the fine-structure interval Δ E fs = E(2 P 3/2) − E(2 P 1/2) and in the hyperfine structure of the 2 P 1/2-and 2 P 3/2-wave energy levels. The resulting values of Δ E fs = 8352.08 µeV, Δ Ẽ hfs(2 P 1/2) = 7819.80 µeV, and Δ Ẽ hfs(2 P 3/2) = 3248.03 µeV provide reliable guidelines in performing a comparison with relevant experimental data and in more precisely extracting the experimental value of the (2 P–2 S) Lamb shift in the muonic-hydrogen atom. [ABSTRACT FROM AUTHOR]

An algorithm for describing operator structures and calculating energy levels for hydrogen-like atoms in the quantum mechanics with nonnegative distribution function (Kuryshkin’s quantum mechanics) is developed. The algorithm is implemented in Maple. An original library of necessary functions and quantities (Coulomb wave functions, Sturm functions, their Fourier images and kernels of integral transformations, Clebsch-Gordan coefficients, products of spherical harmonics, etc.) has been created. In accordance with the quantization rules in Kuryshkin’s quantum mechanics, operators of observable quantities are computed. Based on the Hamiltonian obtained, energy levels of a hydrogen-like atom are calculated by the Ritz method (in the basis of Sturm functions). Numerical values of model parameters are determined by comparing results obtained with experimental data for hydrogen and alkali metals taken from the NIST Atomic Spectra Database Levels Data library. [ABSTRACT FROM AUTHOR]

Antihydrogen (Hbar) was first produced at CERN in 1995. Over the past decade our ATRAP collaboration has made massive progress toward our goal of producing large numbers of cold Hbar atoms that will be captured in a magnetic gradient trap for precise comparison between the atomic spectra of matter and antimatter. The AD at CERN provides bunches of 3 × 107 low energy antiprotons approximately every 90 s. We capture and cool to 4 K, 0.1% of these in a cryogenic Penning trap. By stacking many bunches we are able to do experiments with 3 × 105 Antiprotons. Approximately 100 positrons (e+)/s from a 22 Na radioactive source are captured and cooled in the trap, with 5 × 106 available experiments. We have developed two ways to make Hbar from these cold ingredients, namely three-body collisions, and two-stage Rydberg charge exchange. We have also developed techniques to measure the excited-state distribution of the Hbar and measure their velocity. A new apparatus is being used this year that includes a e+ accumulator built at York University providing many more e+. The new antiproton annihilation detector provides spatial information of annihilations. Windows allow lasers to enter the trap for spectroscopic measurements and for laser cooling of the Hbar. Possibly the most exciting inclusion in this new apparatus is the inclusion of a neutral particle trap which may, for the first time, capture the Hbar and lead to the first atomic spectrum from antimatter. [ABSTRACT FROM AUTHOR]

A procedure for the calculation of the correction to the hyperfine structure of hydrogen-like ions for the Bohr-Weisskopf effect is developed on the basis of experimental data on muonic atoms. The calculations take into account the quantum electrodynamic corrections both for muonic atoms and for electronic ions. The single-particle model and the configuration mixing model of the nucleus are considered. The results of the calculations are compared with known theoretical and experimental data. [ABSTRACT FROM AUTHOR]

The article presents a study on the aspects of classical hydrogen atomic model interacting with electromagnetic radiation. The authors examine the behavior of classical charged point particle, which orbits an infinitely massive and oppositely charged nucleus, while acted upon by polarized electromagnetic plane waves. They state that the study is essential for researchers studying the classical behavior of Rydberg-like atoms. They note that the study also shows implications regarding the behavior of the model within the stochastic electrodynamics theory.

We derive formulas that describe the energy spectrum of a hydrogen atom in a superstrong magnetic field for states with various magnetic quantum numbers. Comparison with available numerical calculations of the spectrum indicates that the results obtained are highly accurate. These results can be interpreted as a manifestation of the Zeldovich effect regarding the rearrangement of the hydrogen atomic spectrum under the influence of strong Coulomb potential distortion at short distances in the problem under consideration. [ABSTRACT FROM AUTHOR]

Abstract: The natural broadening of hydrogen atom spectrum based on the minimal length uncertainty is calculated. We will show that the natural broadening of hydrogen atom spectrum receives any correction. [Copyright &y& Elsevier]

In this study, we examine the atomic and molecular signatures in laser-induced plasma. Abel inversions of measured line-of-sight data reveal insight into the radial plasma distribution. Laser-plasma is generated with 6 ns, Q-switched Nd:YAG radiation with energies in the range of 100 to 800 mJ. Temporally- and spatially-resolved emission spectroscopy investigates expansion dynamics. Specific interests include atomic hydrogen (H) and cyanide (CN). Atomic hydrogen spectra indicate axisymmetric shell structures and isentropic expansion of the plasma kernel. The recombination radiation of CN emanates within the first 100 nanoseconds for laser-induced breakdown in a 1:1 mole ratio CO2:N2 gas mixture. CN excitation temperatures are determined from fitting recorded and computed spectra. Chemical equilibrium mole fractions of CN are computed for air and the CO2:N2 gas mixture. Measurements utilize a 0.64-m Czerny–Turner type spectrometer and an intensified charge-coupled device. [ABSTRACT FROM AUTHOR]

This work communicates a review on Balmer series hydrogen beta line measurements and applications for analysis of white dwarf stars. Laser-induced plasma investigations explore electron density and temperature ranges comparable to white dwarf star signatures such as Sirius B, the companion to the brightest star observable from the earth. Spectral line shape characteristics of the hydrogen beta line include width, peak separation, and central dip-shift, thereby providing three indicators for electron density measurements. The hydrogen alpha line shows two primary line-profile parameters for electron density determination, namely, width and shift. Both Boltzmann plot and line-to-continuum ratios yield temperature. The line-shifts recorded with temporally- and spatially-resolved optical emission spectroscopy of hydrogen plasma in laboratory settings can be larger than gravitational redshifts that occur in absorption spectra from radiating white dwarfs. Published astrophysical spectra display significantly diminished Stark or pressure broadening contributions to red-shifted atomic lines. Gravitational redshifts allow one to assess the ratio of mass and radius of these stars, and, subsequently, the mass from cooling models. [ABSTRACT FROM AUTHOR]

The article offers science news briefs. Researcher Mark Holmes and colleagues of the University of Cambridge in Great Britain have discovered a previously unknown strain of methicillin-resistant Staphylococcus aureus (MRSA), called mecA, while investigating mastitis in British dairy cows that has also been detected in humans. Physicists with the ALPHA experiment at the European Organization for Nuclear Research (CERN) have held antihydrogen atoms for up to 15 minutes.