The projectile K Auger electron emission observed during grazing collisions of 60-keV ${\mathrm{N}}^{6+}$ ions with Au(110) is characterized by two components strikingly different dependences on perpendicular velocity. A ``fast'' component dominates and ascribed to ``subsurface'' emission. This was satisfactorily modeled using a Monte Carlo simulation the trajectories after surface penetration. ``slow'' appears at very small angles has time dependence characteristic...

Absolute total cross-section measurements are presented for electron capture in ${\mathrm{O}}^{5+}$+H(D) collisions over the energy range 0.9--800 eV/amu. These first experimental data to be reported using a new multicharged-ion--atom merged-beams apparatus developed at Oak Ridge National Laboratory. The method and described detail. At energies below 2 eV/amu, show enhancement which may attributed ion-induced dipole attraction between reactants. Agreement with recent unpublished...

Total-electron-capture cross sections are reported for fully stripped and H-like ions of C, N, O, F, Ne colliding with atomic molecular hydrogen targets in the energy range 0.18--8.5 keV/amu. At energies above 3 keV/amu approximately independent magnitudes (4--7)\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}15}$ ${\mathrm{cm}}^{2}$, scale smoothly projectile charge. Below H-target projectiles even charge smaller than those odd For ${\mathrm{H}}_{2}$-target data, opposite...

The method of zero-degree Auger spectroscopy was used to measure cross sections for the production K and L electrons by double electron capture in 60-keV ${\mathrm{C}}^{6+}$+He collisions. Corresponding atomic-structure calculations were performed determine related x-ray transition rates. resulting yields are found deviate significantly from unity. applied evaluate configuration 3lnl' (n=3 5) 2lnl' 8). These data compare well with experimental results obtained previously isocharged system...

Electron energy spectra and total electron yields are studied to provide information on the neutralization of 24-keV ${\mathrm{N}}^{\mathit{q}+}$ ions (q=2,4,6) incident at grazing angles a Cu(100) surface. A computer simulation is presented that assumes resonant leading highly excited ``hollow'' atoms. Deexcitation these atoms assumed take place by purely intra-atomic Auger transitions. The results this not in agreement with our experimental observations. modified simulation, assuming again...

We report the first measurements of ejected-electron-energy distributions from slow glancing collisions highly charged ions having K-shell vacancies with a solid surface. The spectra indicate two competing processes for filling vacancy: one involving normal atomic Auger decay, and other, vacancy transfer to inner shells via molecular orbital pseudocrossings. number electrons per incident ion resulting is order unity, constituting only small fraction total measured yield.

Lyman x-ray spectra following charge exchange between C${}^{6+}$ and H${}_{2}$ are presented for collision velocities 400 2300 km/s (1--30 keV/amu). Spectra were measured by a microcalorimeter detector capable of fully resolving the C vi series emission lines though Lyman-$\ensuremath{\delta}$. The ratios sensitive to angular momentum $l$ states populated during used gauge effectiveness different $l$-distribution models in predicting due exchange. At low velocities, we observe that both...

We report the first experimental study of angular momentum states populated by double-capture collisions multiply charged ions. High-resolution spectra L-Coster-Kronig electrons originating from ${\mathrm{O}}^{4+}$ 1${s}^{2}$2pnl (n=6,7) produced in 30--105-kev ${\mathrm{O}}^{6+}$+He were obtained. Analysis observed spectra, performed with use Hartree-Fock transition energies, indicates population high--angular-momentum states. A classical-model calculation suggests that correlated...

X-ray spectra following charge-exchange collisions between C${}^{6+}$ and He are presented for collision energies 460 32 000 eV/u. Spectra were obtained at the Oak Ridge National Laboratory Multicharged Ion Research Facility using a microcalorimeter x-ray detector capable of fully resolving C vi Lyman series lines through Ly-$\ensuremath{\gamma}$. These line ratios sensitive to initial electron $\ensuremath{\ell}$ distribution test our understanding process. In addition, these important...

We report observation of a significant enhancement in the intensity target and projectile autoionizing electrons produced low-energy (2--15 keV) ${\mathrm{He}}^{+}$+He collisions. The electron is strongly peaked at 0\ifmmode^\circ\else\textdegree\fi{} confined to an angular range \ensuremath{\approxeq}5\ifmmode^\circ\else\textdegree\fi{} about incident beam direction, while shows similar 180\ifmmode^\circ\else\textdegree\fi{}. attribute this effect Coulomb focusing, new aspect post-collision...

Measurements of absolute total cross sections for single-electron capture in collisions ${\mathrm{N}}^{3+}$, ${\mathrm{N}}^{4+}$, and ${\mathrm{N}}^{5+}$ ions with ground-state atomic hydrogen are reported the energy region 0.9--1400 eV/amu. Good agreement is obtained available theoretical calculations previous experimental results at higher energies. None systems studied shows a clear signature induced-dipole attractive force enhancing section.

In preparation of a laser ion source, we have investigated multi-step ionization via Rydberg and autoionizing states for atomic Ni Ge using mass separator with an beam energy 20 keV. For both elements resonant three-step excitation schemes suitable modern Ti:sapphire systems were developed. series in the range principal quantum numbers ⩽ n 80 localized, assigned allocated to individual resonances. Ionization potentials (IP) extracted from fits defects levels analysed confirmation assignment....

We have developed a novel laboratory instrument for studying gas phase, anion-neutral chemistry. To the best of our knowledge, this is first such apparatus which uses fast merged beams to investigate chemical reactions. As proof-of-principle we detected associative detachment reaction H−+H→H2+e−. Here describe in detail and discuss related technical experimental issues.

Charge transfer due to collisions of ground-state N${}^{6+}(1s{\phantom{\rule{0.16em}{0ex}}}^{2}\phantom{\rule{-0.16em}{0ex}}S)$ with atomic hydrogen has been investigated theoretically using the quantum-mechanical molecular-orbital close-coupling (QMOCC) method, in which adiabatic potentials and nonadiabatic couplings were obtained multireference single- double-excitation configuration-interaction (MRDCI) approach. Total, $n$-, $l$-, $S$-resolved cross sections have for energies between 10...

The total-electron-capture cross section for collisions of C${}^{4+}$ with ground-state hydrogen (deuterium) is measured in the energy range 6--1000 eV/u using merged-beam technique. fraction metastable ions present ion beam to be 5%, which results a correction only few percent. independently absolute measurements are generally good agreement previous total electron capture; however, reduced uncertainties these allow more detailed comparison theory. Our observations show that existing fully...

An oscillatory charge dependence of total electron-capture cross sections has been observed for fully stripped projectiles having $6<~Z<~10$ incident on H and ${\mathrm{H}}_{2}$ at collision energies below 3.0 keV/amu. The oscillations are attributed to the discreteness projectile final-state spectrum strong selectivity capture process a given energy. Relative maxima in occur odd case H, even target. This shift is explained terms Landau-Zener curve-crossing picture electron-transfer collision.

A technique based on selective nonresonant laser photodetachment of unwanted negative ion species has been developed for efficient suppression isobaric contaminants in beams. radio-frequency quadrupole guide is employed to cool the beam and dramatically increase interaction time ions with laser, substantially increasing efficiency process. In a proof-of-principle experiment, we achieved 95% Co−59 by while under identical conditions 10% Ni−58 were neutralized.

A comprehensive theoretical and experimental study of electron capture in collisions with H C extending over the energy range to is presented. variety approaches were used including those based on quantal molecular-orbital close-coupling (MOCC), multielectron hidden crossings (MEHC), decay classical trajectory Monte Carlo techniques. Radiative charge transfer cross sections computed using optical potential/distorted wave (OPDW) fully (FQ) approaches. The MOCC, OPDW FQ calculations...

Kinetic energy distributions of electrons emitted in the interaction slow (10q-keV) multicharged ions (N,O,Ne,Ar) with metal surfaces (Cu,Au) are presented. We observe secondary-electron emission, quasielastic-scattering processes, and, superimposed upon this, one-center Auger decay both projectile and target vacancies. Two classes Auger-decay features observed. Long-lived vacancies decay, leading to discrete line features, similar those arising from electron-impact excitation. Short-lived...

Lyman spectra and line ratios are reported for soft-x-ray emissions following the charge exchange process in 293, 414, 586, 1256 km/s ${\mathrm{O}}^{8+}$ Kr collisions. series from Ly-$\ensuremath{\alpha}$ to Ly-$\ensuremath{\varepsilon}$ were resolved ${\mathrm{O}}^{7+}$ ion using a high-resolution x-ray quantum microcalorimeter detector. It is found that observed dependent on $nl$ distribution of captured electron, Ly-$\ensuremath{\beta}$ enhanced. Moreover, by comparing measured...

Measurements and theoretical analyses of total electron-capture cross sections for collisions ${\mathrm{N}}^{4+}$ with ground-state hydrogen (deuterium) are reported in the energy range 1--300 eV/u. The present measurements have reduced relative uncertainty compared to previous absolute at Oak Ridge National Laboratory [Huq et al., Phys. Rev. A 40, 1811 (1989)] used detailed comparison more recent coupled-channel molecular-orbital calculations [Shimakura 45, 267 (1992); Zygelman ibid. 46,...