We have measured differential elastic-scattering cross sections of ozone by electron impact. A crossed-beam method was used. The energy and angular range measured were from 3.0 to 20 eV and from 12° to 156°, respectively. Strong forward and backward scattering was observed as the incident energy increased. Integrated and momentum-transfer cross sections have been obtained from the differential cross sections. The integrated cross sections over this energy range were found to be almost constant in magnitude.

Doubly differential cross sections (DDCS) for the molecular single (${\mathrm{H}}_2^{+}$) and dissociative single (H+${\mathrm{H}}^{+}$) ionization of the hydrogen molecule have been measured employing the ejected-electron and produced-ion coincidence technique for an incident electron energy of 100 eV and ejected-electron energies between 20 and 80 eV. Angular variations of partial and total DDCS’s have also been measured in experiments in which electrons are detected at angles between 2° and 110° relative to the direction of the incident electrons. A comparison of the present measurements has been made with the data from the published literature.

Momentum distributions and spectroscopic factors are obtained in a high-resolution electron-momentum spectroscopy study of xenon at 1000 eV. The shapes and relative magnitudes of the momentum profiles are in excellent agreement with distorted-wave (DW) impulse approximations using the target Dirac-Fock (DF) approximation. The DWDF approximation accurately describes the relative magnitudes of the 5p and 5s manifold cross sections as well as the shape of the 5s cross section. The use of nonrelativistic Hartree-Fock wave functions gives significantly poorer fits to the data. Spectroscopic factors for transitions belonging to the ${}_{}{}^2{}_{}{}^{}$${\mathit{S}}_{1/2}^{\mathit{e}}$, ${}_{}{}^2{}_{}{}^{}$${\mathit{P}}_{1/2,3/2}^{\mathit{o}}$, and ${}_{}{}^2{}_{}{}^{}$${\mathit{D}}_{3/2,5/2}^{\mathit{e}}$ manifolds are assigned up to a separation energy of 45 eV. The spectroscopic strength for the lowest 5s transition is 0.345±0.010 whereas that for the ground-state 5p transition is 0.96±0.02. The 5s strength in the continuum above 33.1 eV is 0.115±0.025 and that for the 5p manifold is only 0.03±0.01. The first momentum profiles belonging to excited ${}_{}{}^2{}_{}{}^{}$${\mathit{P}}^{\mathit{o}}$ and ${}_{}{}^2{}_{}{}^{}$${\mathit{D}}^{\mathit{e}}$ manifolds are obtained. The latter, which must be entirely due to d-wave correlations in the xenon ground state, are in good agreement with DF 5d momentum profiles. Comparison is made with several many-body calculations and agreement with the latest relativistic calculation is good.

We present results for the electron-impact ionization of Li-like, Be-like, and B-like Fe, Kr, and Xe ions. We have included the contributions from direct ionization, excitation autoionization, and dielectronic-capture double autoionization in our calculations. We discuss isonuclear and isoelectronic trends for the various contributions, focusing on the resonance contributions in particular.

The problem of the choice of a trajectory in the time-dependent semiclassical treatment of nonadiabatic molecular collisions is reconsidered. The purpose of the work is to improve the semiclassical description of vibronic transitions in conditions where quantal calculations are hardly feasible. In order to bring out our proposal, the investigation is carried out in the framework of the infinite-order sudden approximation where quantal calculations are tractable and thereby provide a reliable testing ground. The way in which a classical trajectory emerges when deriving the time-dependent equations from the quantal ones is reexamined. Specific features are pinpointed which draw one’s attention to the idea of a multitrajectory approach. A proposal is formulated and applied to vibronic charge transfer in the ${\mathrm{H}}^{+}$+${\mathrm{O}}_2$ collision. The proposed multitrajectory treatment is found to be superior to the other semiclassical treatments based on a simple common trajectory.

Absolute cross sections for simultaneous ionization and excitation by electron impact of 13 4${\mathit{p}}^4$5p levels of Kr ii from its atomic ground state have been measured for electron energies between threshold and 1000 eV. An optical method was employed in the present experiment. The measured maximum cross sections were in the range (15.0–80.1)×${10}^{\mathrm{-}20}$ ${\mathrm{cm}}^2$.

Experimental studies of electrons ejected in ionizing collisions between ${\mathrm{C}}^{+}$, ${\mathrm{C}}^{2+}$, and ${\mathrm{C}}^{3+}$ projectiles and He and Ne targets have been made for incident projectile energies of 83, 100, and 150 keV/u. The data exhibit pronounced maxima in the 10° ejected-electron energy spectra and projectile-charge-dependent shifts of these maxima which strongly supports the hypothesis of an independent ‘‘saddle-point’’ ionization mechanism. A possible cause of disagreement between these results and existing experimental data is also discussed.

The quasimolecular x-ray spectrum resulting from the filling of a 1sσ vacancy during the collision of 117-keV ${\mathrm{Ne}}^{9+}$ ions with Ne atoms has been observed in an x-ray ion coincidence experiment for ions scattered into the range 17.0°–26.0°. The observed spectrum is in reasonable agreement with one calculated using the uniform asymptotic approximation and a previous calculation of the 1sσ-2pπ interval versus the internuclear separation. The model and the data show an interference structure only weakly present due to averaging by the x-ray detector resolution.

A 15-state R-matrix calculation has been carried out at 685 energies ranging from 1–17 eV to depict the resonant profiles for the elastic differential cross sections and the angular distribution of the spin asymmetry ${\mathit{A}}_{1\mathit{s}\mathrm{-}1\mathit{s}}$(θ,${\mathit{k}}^2$) in the elastic scattering of spin-polarized electrons by spin-polarized hydrogen atoms at angles of 30°, 55°, 70°, and 90°. The calculations are compared with experiments.

Triple-differential cross sections for ionization of hydrogen atoms by electrons have been calculated both for small- as well as large-momentum-transfer cases at intermediate (5${\mathit{I}}_0$–20${\mathit{I}}_0$) and high (≳20${\mathit{I}}_0$) energies (${\mathit{I}}_0$ being the ionization potential) following a method which uses a final-channel three-particle wave function determined by one of the authors. This wave function resulted from an analysis of the three-particle wave equation in momentum space and is correct to the first order in the interaction potentials. Incidentally, it is also the first-order Faddeev wave function. The wave function has been suitably normalized before it is used. The computed results are generally good. The small-momentum-transfer results are in nice agreement with the experimental data except for a certain angular region which includes the recoil peak. The domain over which the present results agree in trend with the experimental measurements is somewhat larger than that for the distorted-wave-Born-approximation calculation. Large-momentum-transfer results are also in qualitative agreement with experiments. There are indications that quantitatively the present results may be better there. Total-ionization cross-section results are also in excellent agreement with experiment above 200-eV energy. These facts together with the simplicity of the calculation establish that the present method has certain advantages over other existing methods. The present calculation may be the starting point for a more elaborate calculation which will take into account more accurately the correlation and higher-order effects in the final-channel three-particle wave function.

Partial cross sections for single- and double-electron capture by multiply charged ions (q=4 and 5) in low- and intermediate-energy collisions with He were calculated within the two-electron two-center atomic-orbital coupled-channel method. Special care was exerted to account for electron-correlation effects in the reaction process. Absolute single-capture cross sections compare reasonably well with available experiments. The relative behavior of partial cross sections for double-electron capture as well as the relative population of magnetic substates are in good agreement with experiments for ${\mathrm{B}}^{4+}$(1s) and ${\mathrm{C}}^{5+}$(1s) impact.

The effect of relaxation on KLL, LMM, and MNN Auger-electron spectra of Ne, Mg, Ar, Ca, Zn, and Kr has been studied by the Dirac-Fock method. The relaxation is shown to depend universally on the Auger-electron energy and on the number of peel electrons (${\mathit{N}}_{\mathit{r}}$) in subshells above the final-state holes. In the sudden-approximation limit (large ${\mathit{N}}_{\mathit{r}}$), the relaxation saturates to 14% reduction of the Auger rates in analogy to the 20% reduction of deep inner-shell Dirac-Fock photoionization cross sections well above threshold. The isotropy of the relaxation is emphasized by its small influence on the angular distribution of Auger electrons.

Angle-resolved ratios of the separate triplet and singlet spin channel cross sections have been measured for elastic scattering of spin-polarized electrons from optically pumped spin-polarized sodium atoms. The triplet-to-singlet ratios are reported at incident energies of 4.1, 10.0, and 20.0 eV for scattering angles from 20° to 140°. The data demonstrate that spin-exchange scattering plays an important role in the description of electron scattering from sodium at these energies. Comparisons are made with the results of several close-coupling theoretical calculations.

The relative photoionization cross section of atomic nitrogen across the 2s2${\mathit{p}}^3$${(}^5$${\mathit{S}}^{\mathit{o}}$)np${(}^4$${\mathit{P}}^{\mathit{e}}$) autoionizing states and the β parameter over the 2s→3p and 4p resonances are measured using synchrotron-radiation-based photoelectron spectrometry. Results are compared with a multiconfiguration Hartree-Fock calculation. Resonance energies for autoionizing states from n=3–10 are presented and compared with an eariler experiment. Values of the line-shape parameters Γ, q, and ${\mathrm{\rho }}^2$ and discrete oscillator strengths f for the 3p, 4p, and 5p resonances are reported.

In a high-resolution photoelectron-spectrometry study of the photoionization of chlorine atoms in both the 3s and 3p subshells, we were able to resolve contributions from ionic states with specific J values and measure the relative populations of these fine-structure components. Our photoelectron spectra, recorded at hν=29.2 eV, give ratios of ${}_{}{}^3{}_{}{}^{}$${\mathit{P}}_2$${:}^3$${\mathit{P}}_1$${:}^3$${\mathit{P}}_0$=100:40.59.5 for 3p photoionization and ${}_{}{}^3{}_{}{}^{}$${\mathit{P}}_2$${:}^3$${\mathit{P}}_1$=100:31 for 3s photoionization. While the results for 3p ionization are in accord with predictions based on a simple geometric analysis, the contribution of the ${}_{}{}^3{}_{}{}^{}$${\mathit{P}}_1$ state in 3s photoionization is larger than that predicted by this simple model. The geometric predictions are also compared with results from a similar measurement of the population of the 4${\mathit{p}}^{\mathrm{-}1}$${(}^3$${\mathit{P}}_{\mathit{J}}$) states produced in the 4p ionization of Br and with earlier work on the production of ${}_{}{}^3{}_{}{}^{}$${\mathit{D}}_{2,1,0}$ states in d-shell photoionization of Cu and Ag.

In this, the first of two papers, we obtain a simple analytic formula for the photodetachment cross section of ${\mathrm{H}}^{\mathrm{-}}$ in crossed electric and magnetic fields. The three-dimensional semiclassical approximation predicts oscillations in the spectrum and these oscillations are correlated with closed classical orbits. In the following paper [A. D. Peters and J. B. Delos, Phys. Rev. A 47, 3036 (1993)] we derive fully-quantum-mechanical formulas for the cross section in perpendicular electric and magnetic fields and show how these results can be reduced to the semiclassical results of this paper.

In this, the second of two papers, we derive general quantum formulas for the photodetachment cross section for ${\mathrm{H}}^{\mathrm{-}}$ in perpendicular electric and magnetic fields. The results are valid for any polarization and can be reduced to the semiclassical results of the first paper [A. D. Peters and J. B. Delos, Phys. Rev. A 47, 3020 (1993)]: a smooth background plus oscillatory terms. This connection between the quantum and semiclassical results is made using a stationary-phase approximation and it is shown that each stationary-phase point corresponds to a closed orbit.

A recent model of particle transport in plane-parallel media, including both quasielastic and inelastic scattering, has been proposed [Goulet et al., Phys. Rev. A 41, 6006 (1990)] which claims to be fully three dimensional, to include the effects of multiple scattering, and to avoid the normal difficulties associated with such problems. The present paper demonstrates that a transport problem is being solved and that the method used is of comparable accuracy to elementary diffusion theory. It is shown that the model, applied here to the low-energy-electron transmission and reflection spectroscopy problem, is valid only under a fairly stringent assumption on the interface scattering at the boundaries of the layer. The model is rederived for this case in terms of standard transport theory. A comparison of the two models points to an ambiguity in the interface reflectivity in the previous model. In addition the method presented here leads to a more satisfactory application of the Snell-Descartes law and a full solution in terms of known functions.

The stopping power of antiprotons moving at energies up to 400 keV through a uniform zero-temperature electron gas is calculated within the framework of the kinetic theory. The momentum-transfer cross section required is determined with the aid of a parametric velocity-dependent scattering potential. A nonperturbative constraint, provided by the nuclear-cusp condition, is used to fix the parameter value. A comparison with the result of a quadratic-response-function approach is made. The calculated stopping powers are in good agreement with recent experimental predictions.

The continuum-distorted-wave–eikonal-initial-state model is applied to the calculation of charged charge-state electronic stopping powers. The contributions from electron capture, excitation, and ionization are evaluated for p¯, ${\mathrm{H}}^{+}$, ${\mathrm{He}}^{2+}$, and ${\mathrm{Li}}^{3+}$ projectiles impinging on H targets at energies of 10–1000 keV/amu. With the neutral H charge-state electronic stopping power obtained from the first Born approximation, charge-state fractions and total mean electronic stopping powers for ${\mathrm{H}}^{+}$ beams traversing H are calculated. Present results are compared with calculations using the first Born approximation, a one-center atomic-orbital coupled-channel code, and experimental data for ${\mathrm{H}}_2$ targets.