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The energy levels and spectral lines of multiply ionized tungsten atoms, W2+ through W73+, have been compiled. Experimental data on spectral lines and energy levels exist for the spectra of W III through W VII, W XXVIII through W LI, W LIII, and W LV through LXV. For W VIII, the four lowest energy levels were derived from the series limits of W VII. For W LXIV (Na-like) and W LVI (K-like), we supplement experimental data on energy levels and wavelengths with predicted values found by accurate interpolations and extrapolations along the isoelectronic sequences. For W LXXIII (He-like) and W LXXIV (H-like), theoretical data on energy levels and line wavelengths are compiled. For W III, we include experimentally determined radiative transition probabilities where available. The ground state configurations and terms were determined for all stages of ionization. A value of ionization energy is included for each ion.

The energy levels and spectral lines of gallium atom in all stages of ionization have been compiled. Experimental data on spectral lines and energy levels exist for spectra Ga I through Ga VII, Ga XIII through Ga XXVI, and Ga XXX. For Li-like Ga XXIX through H-like Ga XXXI, theoretical data on energy levels and line wavelengths are compiled. For Ga I, Ga II, and Ga III we include radiative probabilities of electric-dipole transitions where available. For Ga XV through Ga XX, Ga XXIII through Ga XXVI, and Ga XXX, radiative probabilities of magnetic-dipole and electric-quadrupole transitions are included. The ground state configuration and term and a value of ionization energy are included for each ion.

Cross sections for 74 processes in collisions of electrons with nitrogen molecules (N2) and singly ionized nitrogen molecules ( N 2 + ) have been collected. The literature has been surveyed through the middle of 2004. The data sets collected are presented in separate graphs for each process. Recommended cross sections are expressed by analytic expressions.

Energy levels, wavelengths, and transition probabilities of the first and second spectra of tungsten, W I and W II, have been compiled. Wavelengths of observed transitions and energy levels derived from those wavelengths have been obtained from a critical evaluation of the available literature. Measured transition probabilities for some of the observed transitions have been compiled from the published literature.

We have measured single- and multiple-charge transfer cross sections of 2q keV Neq+ (q=2–6) and Arq+ (q=2–9) ions in collisions with CH4, C2H2, C2H4, C2H6, C3H4 [allene, propyne], C3H6, (CH2)3, and C3H8 molecules. Cross sections for total charge transfer were derived by summing up single- and multiple-charge transfer cross sections. Their gross features and scaling properties for the present polyatomic molecules as functions of the incident charge number of primary ions and first ionization potentials of target particles are found to be able to be represented by a scheme of a classical over-barrier model for atomic and simple molecular targets. Apart from the ionization potential, dependences of the present total charge transfer cross sections are found on total number of electrons and the number of bonds in target hydrocarbons.

Cross section data in the energy range above 1 eV have been critically evaluated for electron impact collision processes involving the impurity species (CO, CO 2 , and H 2 O) most relevant to low-temperature plasmas. A short review of the cross section measurements is given for each collision process. The literature has been surveyed up to December 1999. Analytic fits to the recommended cross sections are also presented.

The role of multiple-scattering events has been investigated in single ionization of atoms induced by energetic ion impact. The triply differential cross sections have been evaluated as a function of the projectile scattering angle for fixed values of the emitted electron energy and angle within the framework of the distorted-wave Born approximation (DWB). It has been shown that the double-scattering mechanism, which (sometimes) results in a characteristic double-scattering peak at a definite projectile scattering angle, provides a satisfactory description of the process over a wide region of electron ejection energies and angles. For low-energy electron emission the role of higher orders is not negligible, and the quantum mechanical nature of the process is more emphasized. At an electron velocity equal to the projectile velocity the analogy with the mechanism of electron capture into bound states has also been investigated. In this region the DWB theory for ionization corresponds to the Oppenheimer-Brinkman-Kramers model for electron capture.

Analytic expressions fitted to cross section data on collisions of H + , H + 2 , H 3 + , H, H 2 , and H − with H 2 are given. The data used are those recommended by Phelps [J. Chem. Phys. Ref. Data 19 , 653 (1990)] and additional experimental data, when available, up to a projectile energy of about 100 keV, including new kinds of reactions not treated by Phelps. The analytic expressions are of the semiempirical functional forms proposed by Green and McNeal [J. Geophys. Res. 76 , 133 (1971)] and modifications of these, thus making it possible not only to interpolate but also to extrapolate the data to some extent.

Theoretical calculations of the electron capture cross sections in collisions of beryllium ions with helium atoms are performed in a close-coupling method based on molecular-state expansion for the Beq + (q = 2,4) ion impacts below 35 keV amu-1, and in the continuum distorted-wave method for the Beq + (q = 1-4) ion impacts above 100 keV amu-1. The present results are discussed in comparison with other available theoretical calculations.

In high-energy atomic collisions between bare high-$Z$ projectiles and low-$Z$ target atoms, an electron may be captured radiatively into the ground state or, alternatively, into an excited projectile state, which subsequently decays by x-ray emission. These processes are the inverse of a single-step or a two-step ionization, in which the first photon resonantly excites an electron from the hydrogenic ${1s}_{1/2}$ ground state and a second photon ionizes the excited electron. In this paper, we present a theoretical analysis with a particular emphasis on a detailed multipole decomposition of the photon wave function. This treatment is suitable for connecting angular correlations with alignment studies of the excited state. The anisotropy factors for angular correlations beween the beam axis and the decay x rays following radiative electron capture (REC) into the ${2p}_{3/2}, {3p}_{3/2}, {3d}_{3/2},$ and ${3d}_{5/2}$ levels of bare ${\mathrm{Xe}}^{54+}, {\mathrm{Au}}^{79+}, {\mathrm{Pb}}^{82+},$ and ${\mathrm{U}}^{92+}$ projectiles with energies ranging from 10 MeV/u to 10 GeV/u are explicitly presented and the connection with the alignment is given. It is predicted that REC occurs predominantly into states with the minimal magnetic quantum number $\ifmmode\pm\else\textpm\fi{}\frac{1}{2}$ indicating a strong alignment perpendicular to the beam axis.

In high-energy atomic collisions between bare high-Z projectiles and low-Z target atoms, an electron may be captured radiatively into an excited projectile state which subsequently decays by x-ray emission. This process is the inverse of two-photon{endash}one-electron ionization, in which the first photon resonantly excites an electron from the hydrogenic 1s{sub 1/2} ground state and a second photon ionizes the excited electron. We present an experimental and theoretical study of the angular distribution of the Ly-{alpha}{sub 1} (2p{sub 3/2}{r_arrow}1s{sub 1/2} ) x rays following radiative electron capture. From the observed anisotropic emission pattern a significant alignment of the intermediate 2p{sub 3/2} state is deduced. {copyright} {ital 1997} {ital The American Physical Society}

Cross sections for ion production in the D++H2, D++D2, and H++D2 collisions have been calculated in the center‐of‐mass collision energy range of 2.5 to 8.0 eV by using trajectory‐surface‐hopping method on ab initio potential energy surfaces. For the production of H+ and HD+ ions in the D++H2 collisions the present results agree with experiments. For the production of D+2 ions in the D++D2 collisions the calculations show agreement with the experimental results at energies below 4.5 eV, but lead to an overestimate above 5.0 eV. For the production of D+ and HD+ ions in the H++D2 collisions, agreement between the calculations and experiments is good in the whole energy range, while a deviation comes out between both the results for the charge transfer H++D2→D+2+H above 5.0 eV. As far as the energy dependence of cross sections is concerned, the present calculations well reproduce all the experiments, owing to the use of the ab initio surfaces, instead of the diatomics‐in‐molecules surfaces.

Cross sections have been measured for single, double and triple electron capture by C q + ( q =1–4) ions from H 2 , CH 4 , C 2 H 6 , C 3 H 8 and CO 2 molecules in the energy range of (1–20) q keV. The cross sections obtained here exhibit little dependence on the incident energy. Compared with the previous scaling laws, the present cross sections revealed a much stronger dependence on the first ionization potential of the molecules. For hydrocarbon molecules including H 2 all the cross sections show a remarkable linearity on the number of compositeatoms. The single electron capture cross sections σ q , q -1 are compared with the classical over barrier model and with the Olson model which was slighty modified so as to be applied to the molecular targets.

Wavelengths, energy levels, ionization energies, line classifications, intensities and transition probabilities for Kr V through Kr XXXVI, ;with the exception of Kr XI through Kr XVII, are tabulated. No data have been published for Kr XI through Kr XVII. These data are based on the energy levels compilation of Sugar and Musgrove [13]. Transition probabilities for selected M1 lines have been reported and are quoted here. A short review of the line identifications and wavelength measurements is given for each stage of ionization. The literature has been surveyed through February 1995.

Based on systematic experimental studies and on exact relativistic calculations of the REC process in relativistic heavy-ion atom collisions, the limits of applicability of the nonrelativistic dipole approximation are discussed. In particular, direct comparison between a general REC scaling law and all available total electron-capture cross sections related to REC into bare and H-like ions is given. Similar to K-REC, a fortuitous agreement between the nonrelativistic approach and the experimental data is found. Moreover, the results of a dedicated L-REC experiment are presented, where this process was investigated for energy-resolved subshells. The measured angular distributions for REC into the j = 1 2 and j = 3 2 levels are in excellent agreement with exact relativistic calculations and manifest a complete breakdown of the nonrelativistic theory.

A detailed discussion is given of the general behavior of differential cross sections for radiative electron capture in relativistic and nonrelativistic heavy-ion--atom collisions. From angular-momentum conservation and a simple approximate treatment, the basic qualitative features can be derived in an analytic form. Subsequently, the results of rigorous relativistic calculations are presented graphically for a sequence of projectile charges and projectile energies. It is shown that in radiative electron capture, the influence of the electron spin manifests itself in a particularly clear-cut way.

Measurements of the photon angular distribution of Radiative Electron Capture into the M shell have been performed with He-like uranium ions in the range 110–140 MeV/u. In addition, L REC was studied at a projectile energy of 140 MeV/u. In both cases, the experimental data show an asymmetry around 90° and agree well with a fully relativistic theory.

Energy and charge dependence of total cross section for ionization of the excited states with n\ensuremath{\le}5 of hydrogen, in collisions with the bare ions up to ${\mathrm{O}}^{8+}$, has been investigated theoretically by using the continuum distorted wave\char21{}eikonal initial state (CDW-EIS) approximation. In contrast with the similar calculations of Fainstein et al. [J. Phys. B 23, 1481 (1990)], the present results show that the CDW-EIS approximation becomes identical to the Born approximation at high energies, even in the ionization of excited states. A comparison is made between the present results and other theoretical predictions.

Antihydrogen formation cross sections are calculated for low-energy collisions of antiproton with positronium by the hyperspherical coupled-channel method. The scattering wavefunctions are expanded in terms of a large number of sector-adiabatic states associated with the n=1-4 states of antihydrogen and n=1-3 states of positronium in the asymptotic separated-atom region. The present formation cross sections differ considerably from those of the unitarized Born approximation reported by Mitroy and Stelbovics (1994). The disagreement becomes larger with decreasing collision energy owing to the different energy dependence of the cross sections. The authors have confirmed that the formation cross sections from the 2s and 2p states are larger than that from the ground state by one order of magnitude.

Critically evaluated wavelengths, energy levels, ionization energies, line classifications, oscillator strengths, and atomic transition probabilities for Mn VII to Mn XXV are tabulated. A short review of the line identifications and wavelength measurements is given for each stage of ionization. Grotrian diagrams are also presented to provide graphical overviews. The literature has been surveyed to December 1991.

An analysis of the vibrational spectra of the bent triatomic molecules HCO and DCO has been performed using algebraic methods. A model based on coupled U(2) algebras has heen proposed for the description of the vibrational spectrum of HCO. The vibron model, based on the U(4) Lie algebras, has then been applied for the calculation of the vibrational spectra of the HCO and DCO molecules. The calculated spectra have been compared with the available experimental data as well as with ab initio calculations. The results show that the vibron model provides a description of the experimental data of comparable accuracy to that provided by ab initio calculations.

The available theoretical cross-section data for electron capture into specific (n, l) states in collisions of C6+ and O8+ ions with ground-state hydrogen atoms have been critically assessed. By applying appropriate consistency checks, including comparison with the experimental emission and total cross sections, a set of recommended state-selective electron-capture cross sections σnl has been derived for 3 ≤ n ≤ 8 for C6+ + H and 4 ≤ n ≤ 9 for O8+ + H, with specified accuracy. The recommended cross sections σnl and their sum over l, σn, are presented in graphical form in the energy range from approximately 20 keV/amu (or lower for the dominant channels) to approximately 1 MeV/amu. Analytical fits to the recommended cross sections and fitting parameters are also presented.

Wavelengths, energy levels, ionization energies, line classifications, oscillator strengths, and atomic transition probabilities for Cr v to Cr XXIV are tabulated. A short review of the line identifications and wavelength measurements is given for each stage of ionization. Grotrian diagrams are given to provide graphical overviews. The literature has been surveyed through December 1991. §

Cross sections for the capture of electrons from single-electron targets into bare projectiles moving at relativistic velocities are calculated using the relativistic eikonal approximation. The calculations are performed for projectile energies between 0.2 and l04 GeV/u and for projectile-target combinations that presumably are of interest for future experiments, namely Au and U colliding with C, Al, Cu, Ag, Au, and U and vice versa. State-to-state cross sections are given for initial and final 1s1/2, 2s1/2, 2p1/2 and 2p3/2 states.

A close-coupling calculation with 1s, 2s, and 2p states has been carried out for the 1s-2s,2p excitations of hydrogenlike ions by electrons with an energy lower than 2.5 times the excitation energy. Differential cross sections show a strong dependence on both nuclear charge and impact energy, especially for the 1s-2s excitation. A scaling relation for differential cross sections is well satisfied for the 1s-2p transition. A comparison is made between the present result and other theoretical calculations.

Wavelengths, energy levels, level designations, oscillator strengths, and atomic transition probabilities for the vanadium ions V VI to V XXIII are tabulated. A short review of the line identifications and wavelength measurements is given for each stage of ionization. Grotrian diagrams are also presented to provide graphical overviews. The literature has been surveyed to September 1991.

Wavelengths, energy levels, level classifications, oscillator strengths, and atomic transition probabilities for the cobalt ions Co VIII to Co XXVII are tabulated. A short review is given for the wavelength measurements on each stage of ionization. Grotrian diagrams are also presented to provide graphical overviews. The literature has been surveyed to March 1990.

The vibrational excitation mechanism has been included in the algebraic-eikonal approach to the electron--polar-molecule collision process. A dipole operator that can induce vibrational transitions has been used, and a technique for the evaluation of the matrix elements required for the calculation of the scattering amplitude in the Glauber approximation has been developed. In addition to the long-range dipole interaction, the quadrupole interaction has been included in the same framework in order to improve the potential description of the collision process. Numerical calculations are shown for electron-induced rotational-vibrational excitation through the dipole and dipole-plus-quadrupole interactions.

Wavelengths, energy levels, level classifications, intensities, and transition probabilities for the copper spectra Cu X to Cu XXIX are compiled. The data are critically evaluated and the best results, in the author’s judgment, are quoted. A short review of the work on each stage of ionization is included. Grotrian diagrams are also presented to provide graphical overviews. The literature has been surveyed to March 1990.

Wavelengths, energy levels, level classifications, oscillator strengths, and atomic transition probabilities of the iron ions Fe viii to Fe xxvi are critically reviewed and tabulated. Grotrain diagrams are also presented to provide graphical overviews. The literature has been surveyed to March 1988.

We perform an extension of the continuum-distorted-wave (CDW) approximation for single electron capture by introducing model potentials to describe the interaction of the active electron with the residual-target and projectile ions. The cross sections for electron transfer in collisions of bare and dressed projectile ions with H and He atoms are calculated and compared with experimental data and previous CDW calculations that make use of approximate analytical wave functions to represent the active electron initial and final states. For electron capture in proton-He collisions into definite final states the present calculations are in better agreement with experiments. We trace the differences in the results from both models to a different behavior at projectile scattering angles close to the Thomas peak. In the case of dressed projectiles with different charge states impinging on H and He the present version of CDW gives a better representation of the filling of the unoccupied orbitals of the dressed ion and, therefore, of the cross section as a function of the impinging ion charge state.

L. Gulyas, T. Kirchner, T. Shirai, and M. Horbatsch Japan Atomic Energy Research Institute Tokai-mura, Ibaraki, 319-1195, Japan Institute of Nuclear Research of the Hungarian Academy of Sciences (ATOMKI), P.O. Box 51, H-4001 Debrecen, Hungary Department of Physics and Astronomy, York University, Toronto, Ontario, Canada M3J 1P3 ~Received 16 March 2000; revised manuscript received 25 April 2000; published 5 July 2000!

collisions with CO and CO2 molecules in the energy range of 0.35 to 3.0 keV per initial charge number based on the initial growth rate method. Most of the present single- and multiple-charge-transfer cross sections show weak energy dependence over the observed collision energy range. For CO2 molecules, the present data smoothly join with the previously measured data in the energy range greater than 10 keV. The cross sections for total charge transfer, which are summations of single- and multiple-charge-transfer cross sections, are compared with a simple over-barrier model and available scaling laws.

The hyperspherical coupled-channel method is applied to the positron-helium scatterings in a low-energy region below 54.4 eV. An independent electron model is used for the helium atom under the approximation that the active electron is bound by a central model potential. All the hyperspherical adiabatic states associated with Ps(n,l; n=1-4, l=0-2) and He(1snl; n=1-5, l=0-3) in the separated-atom limit are coupled for the expansion of the scattering equation, which is solved by means of a hybrid procedure of the diabatic-by-sector and the conventional adiabatic-basis-expansion methods. Excellent agreement is obtained with experiment for the positronium formation. \textcopyright{} 1996 The American Physical Society.

In high-energy atomic collisions between bare high-Z projectiles and low-Z target atoms, an electron may be captured radiatively into the projectile [radiative electron capture (REC)]. The photon angular distributions can be very well represented by radiative recombination (RR) of the projectile with free electrons. This process is the inverse of the photoelectric effect. In this paper, we present exact differential RR cross sections for ${\mathrm{Au}}^{79+}$ and ${\mathrm{U}}^{92+}$ at projectile energies of 0.2, 0.5, 1, 2, 5, and 10 GeV/u. We also show the differential cross sections for the photoelectric effect at x-ray energies corresponding to the former projectile energies. It is seen that because of the dramatic forward-peaking of the cross sections at high energies, measurements of REC from low-Z targets are the most practical way to study the photoelectric effect. In one particular example, 10.8 GeV/u ${\mathrm{Au}}^{79+}$ on Au targets, we show that the RR cross section multiplied with the number of target electrons is very close to the REC cross section calculated within the impulse approximation. \textcopyright{} 1996 The American Physical Society.

Total cross sections have been examined theoretically by using the continuum distorted wave\char21{}eikonal initial state (CDW-EIS) and the plane-wave Born approximations for the ionization of hydrogenlike ions in the excited states with the principal quantum number n\ensuremath{\le}5 in collisions with bare ions in the keV/amu to MeV/amu range. For the ionization of hydrogenlike ions up to ${\mathrm{C}}^{5+}$(1s) by ${\mathrm{H}}^{+}$ at low energies, the present CDW-EIS prediction is in good accord with close-coupling calculation, while the Born prediction leads to a considerable overestimate. A comparison is made between the present results and other theoretical predictions as well as experimental measurements.

The process of radiative electron capture (REC) in relativistic collisions of high-Z ions with low-Z gaseous and solid targets is studied experimentally and theoretically. The observed x-ray spectra are analyzed with respect to photon angular distributions as well as to total K-REC cross sections. The experimental results for angle-differential cross sections are well reproduced by exact relativistic calculations which yield significant deviations from standard ${\mathrm{sin}}^{2}$\ensuremath{\theta} distributions. Total cross sections for K-REC are shown to follow a simple scaling rule obtained from exact relativistic calculations as well as from a nonrelativistic dipole approximation. The agreement between these different theoretical approaches must be regarded as fortuitous, but it lends support to the use of the nonrelativistic approach for practical purposes.

Erratum Erratum to ‘‘Analytic cross sections for electron impact collisions with nitrogen molecules’’ [At. Data Nucl. Data Tables 92 (2006) 375–406] Tatsuo Tabata a,b, Toshizo Shirai c,1, Masao Sataka d, Hirotaka Kubo e,∗ a Osaka Prefecture University, 1-1 Gakuen-cho, Naka-ku, Sakai, Osaka 599-8531, Japan b Institute for Data Evaluation and Analysis, 198-51 Kami, Nishi-ku, Sakai, Osaka 593-8311, Japan c Department of Fusion Plasma Research, Japan Atomic Energy Research Institute, Naka-shi, Ibaraki 319-0193, Japan d Tokai Research and Development Center, Nuclear Science Institute, Japan Atomic Energy Agency, 2-4 Shirakata-shirane, Tokai-mura, Ibaraki 319-1195, Japan e Fusion Research and Development Directorate, Japan Atomic Energy Agency, 801 -1 Mukoyama, Naka-shi, Ibaraki 319-0193, Japan

The photon angular distributions for radiative electron capture (REC) into the $j=\frac{1}{2}$ and $j=\frac{3}{2}$ $L$ subshell levels were measured and calculated for ${\mathrm{U}}^{90+}$ \ensuremath{\rightarrow} C collisions at 89 MeV/u. The experiment provides the first study of the photon angular distribution of REC into a projectile $p$ state ($j=\frac{3}{2}$) which was found to exhibit a slight backward peaking in the laboratory frame. For radiative capture to the $j=\frac{1}{2}$ states, the measured angular distribution deviates considerably from symmetry around 90\ifmmode^\circ\else\textdegree\fi{}. The results demonstrate that the usual ${sin}^{2}{\ensuremath{\theta}}_{\mathrm{lab}}$ distribution is not valid in the high-$Z$ regime.

Muon transfer and elastic scattering in low-energy collisions of [ital t]+[ital d][mu](1[ital s]) are studied by the hyperspherical coupled-channel method in which many closed channels are explicitly coupled to obtain converged cross sections. A hybrid procedure of the diabatic-by-sector and the traditional adiabatic-basis-expansion methods is developed for solving a larget set of coupled equations influenced by the nearly singular nature of couplings induced by numerous avoided crossings. It is shown that the adiabatic states belonging to the [ital n]=2 excited states in the separated-atom limit contribute significantly to the muon transfer. The discrepancy between the previous hyperspherical calculation of Fukuda [ital et] [ital al]. [Phys. Rev. A 41, 145 (1990)] and other existing theoretical calculations has been resolved by taking into account the couplings with these excited states.

Radiative electron capture (REC) from a low-Z target atom into a bare high-Z projectile is described in the impulse approximation for the momentum distribution of the captured electron in the initial target state. Otherwise the treatment is rigorous by using exact relativistic Coulomb wave functions for the bound and continuum projectile states. As an application of the computer program, photon spectra and differential cross sections have been calculated for 295-MeV/u ${\mathrm{U}}^{92+}$+N collisions. The angular distributions for K-shell REC as well as for L-shell REC show pronounced deviations from ${\mathrm{sin}}^{2}$\ensuremath{\theta}. Cross sections for radiative recombination with capture into the K shell and into the L subshells are presented for projectile charges between 20 and 100 and for energies between 100 MeV/u and 2 GeV/u.

1. W VII line list (Table 10): upper term labels for the 4f(F5=2)4p 5f (5/2,5/2)1 and (5/2,7/2)1 were, by mistake, interchanged in the line list. 2. WXXXIX levels list (Table 34), bottom line: configuration label was misprinted as ‘‘4p(P1=2)5s”, must be ‘‘4p (P3=2)5s”. 3. W XL line list (Table 37), bottom line: lower-level J value misprinted as ‘‘3/2”, must be ‘‘7/2”. 4. W XLIV line list (Table 45): Line with observed wavelength 5.7928 A: observed wavenumber misprinted as 17230 [10 cm ], must be 17262.8. Line with observed wavelength 5.7951 A: observed wavenumber omitted by mistake, the value (in units of 10 cm ) must be 17256.0. Bottom line (with wavelength 134.81 A): lower term label misprinted as ‘‘P1=2”, must be ‘‘ P3=2”. 5. W XLV levels list (Table 46), level 3d4s4d (1/2,5/2)2: the energy value was misprinted as 2998.5 [10 cm ], must be 2988.5. 6. W XLV line list (Table 47): Line with wavelength 5.7676 A: observed wavenumber was misprinted as 17144 [10 cm ], must be 17338.2. Third line with observed wavelength 7.332 A must be deleted. 7. W XLVI levels list (Table 48): for four energy levels the energy value was misprinted as 25420 [10 cm ]. The correct value is 25426. 8. W XLVI line list (Table 49): The observed wavenumber of the line at 5.9127 Awasmisprinted as 16898 [10 cm ]. The correct value is 16912.7. Line with wavelength 18.635 A: lowerlevel term label was misprinted as ‘‘S3/2”, must be ‘‘D3/2”.

The electron capture processes in collision of highly charged ions with neutral atoms in a strong magnetic field are investigated in the case of arbitrary field direction. A semiclassical molecular-orbital close-coupling method is employed. The phase factors arising from the electron translation factor and the gauge transformation are included. We apply this method to the singlet (B4+ + H) system which have been investigated previously by us only for the field direction being along with the incident velocity vector. The total cross section averaged over field direction increases with field strength. When the field direction is perpendicular to the collision plane, the field effects become maximum.

Analytic formulas are given for the total cross sections sigma for charge transfer collisions of hydrogen atoms and ions with gaseous atoms and molecules. The cross sections considered are sigma/sub 10/, sigma/sub 0//sub -//sub 1/, sigma/sub 1//sub -//sub 1/, sigma/sub 01/, sigma/sub -//sub 10/, and sigma/sub -//sub 11/, where the subscripts represent the initial and the final charge state of the hydrogen. The functionl forms of the formulas are modifications of the semiempirical formula for sigma/sub 10/ given by Green and McNeal. Values of adjustable parameters in the formulas have been determined by least-squares fits to a compiled set of experimental data and are given in a table. The curves given by the formulas are plotted in graphs together with the data. The root-mean-square deviation of the data from the formulas is typically about 20% except when there are large discrepancies among the measurements. Experimental data through 1982 are shown on the graphs; references through mid-1986 are listed. copyright 1987 Academic Press, Inc.

The cross sections for the processes: A (z A -1)+ (1s)+H(1s)→A z A + +e+H, were calculated in the classical binary-encounter approximation (BEA,), where the H + and e in H are assumed to separately collide with the ion, and in the plane-wave Born approximation (PWBA), where the contributions due to the stripping reactions by H + and e in the scattering amplitude.are superposed. The cross sections are evaluated for the processes which produce H(1s)(σ A ) and those which produce excited and ionized H(σ A ) in the final state. For ions with Z A ≥6, the BEA total cross sections, scaled with respect to Z A , agree with those (σ A +σ B ) calculated in the PWBA to within a factor of 1.1 at relative velocities less than 1.5 a.u. and within a factor of 1.5 up to 10 a.u. In the PWBA approximation, the average excitation energy for atomic hydrogen is introduced in order to evaluate σ B , while the cross section becomes independent of this energy at sufficiently high incident energies. In the BEA, such an average exc...