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We measured resonant coherent excitation of a 2s electron of 83.3 MeV/u Fe 23+ ions planar-channeling in the ( 2 ¯ 2 0 ) plane of the silicon crystal. A silicon surface barrier detector (SSD) was used as a crystal target in order to obtain information on the ion trajectory in the channel since the energy deposit ( Δ E ) to the SSD gives information on the ion trajectories where the resonant transitions occur. For the low Δ E , i.e., near the channel center, optically allowed 2s–3p transitions were much stronger compared with other transitions. Increasing Δ E , i.e., increasing the amplitude of ion trajectory, the optically forbidden 2s–3s transition rapidly became strong. On the other hand, the optically forbidden 2s–3d transitions did not become strong as rapidly as 2s–3s transition. Furthermore, it was found that the transition energies to the n = 3 states changed with Δ E . The shifts of the transition energies were consistent with the estimation for the energy levels of the Stark-mixed n = 3 states depending on the distance from the channel center.

K X-rays emitted from 2.1 keV/u N ions transmitted through a thin Ni microcapillary foil were measured in coincidence with a final charge state qf, using a Si(Li) X-ray detector in the cases of incident charge states of qi = 7 and 6. It was found that (1) the coincidence X-ray yield for (qi, qf) = (7, 6) decreased faster than those for other (qi, qf) combinations, (2) the coincidence X-ray yields did not depend on the number of K-shell holes of the incident ions but on the final charge state qf.

Multiple ionization processes of argon atoms by a linearly polarized laser light with the maximum peak intensity of about 5 × 1015 W cm−2 were investigated by the recoil-ion momentum spectroscopy. Momentum distributions of argon ions with charge states 3+ and 4+ were measured. The experimental results were compared with calculations based on the sequential ionization model and the ADK ionization rate [M.V. Ammosov et al., Zh. Eksp. Teor. Fiz. 91 (1986) 2008 (Sov. Phys. JETP 64 (1986) 1191)]. The calculated widths of the distributions agreed with the experimental results to within 30%.

We have made coincidence measurements between L X-rays and final charge states of highly-charged Ar ions passing through a Ni microcapillary thin foil to study the formation and relaxation processes of hollow atoms. By using N6+ projectile ions which have single K-shell hole, Ninomiya et al. [Phys. Rev. Lett. 78 (1997) 4557] showed the existence of long lived excited states formed by multiple electron transfer from a Ni microcapillary thin foil. To further study the formation and relaxation dynamics, such experiments were extended to Ar ions with multiple L-shell holes. The yields of L X-rays from Ar ions, which have one stabilized-electron, decrease faster than those from ions with multiple stabilized-electrons, when the projectiles have multiple inner shell holes.

To detect weak X-rays with a high-resolution spectrometer, a charge-coupled device was operated in a single X-ray photon detection mode. A procedure to effectively identify single X-ray was established. In the case of 2.3 keV/u N7+ and Ne9+ incidence, X-rays emitted from ions transmitted through a Ni microcapillary target were measured with the spectrometer using the procedure of the single event mode. The signal-to-noise ratio was improved by using the single photon counting method.

Ultrasonic signals of near-MHz frequencies were observed when solid targets of Al2O3, KCl and metallic aluminum were irradiated with fast heavy-ions. The projectile beam of 26 MeV/u Xe ions were chopped to pulses shorter than 1 ls. Two piezoelectric sensors detected the acoustic signals at the both ends of the target. The signals were analyzed by Fourier transform and several peaks were observed in the frequency range from several hundred kHz. Amplitudes of the frequency components were nearly proportional to the number of the ions in the pulse. ” 2000 Elsevier Science B.V. All rights reserved.

The single-electron capture processes in collisions of ions with He atoms have been studied at a collision velocity of 3.17 atomic units (au) through a state-selective measurement of differential cross sections. Cold-target recoil-ion momentum spectroscopy (COLTRIMS) has been employed to identify the final state of the captured electron and the momentum transfer between the collision partners. Relative differential cross sections for the capture to 3s, 3p n = 4, and n = 5 orbitals of Ar ions are obtained and are in qualitative agreement with a semiclassical close-coupling calculation using the molecular-state expansion method. The electron is dominantly captured to the n = 5 orbitals, which is in accordance with recent observations at lower velocities.

Using high resolution recoil-ion momentum spectroscopy we have measured differential cross sections of single-electron capture from He atoms by multiply charged boron ions, bare and hydrogen-like , at 0.5 - 1.0 MeV/u. From the measurements of the longitudinal momentum distribution of the recoil ions, the final states of the captured electron in and ions were analysed and the n = 1 ground states were clearly separated from the other excited states. Capture to the excited states gives the dominant contribution to the capture cross section. However, the fraction of captures to the ground state increases with the collision energy. Theoretical calculations based on the eikonal approximation well reproduces the experimental transverse recoil-ion momentum distribution of capture to both the ground and excited states.

Using high-resolution recoil-ion momentum spectroscopy we have measured the differential cross sections of single-electron capture and target single-ionization processes for 8.7 MeV O7+-He collisions as functions of scattering angle. A transverse momentum resolution of +or-0.2 au, which corresponds to an angular resolution of about +or-1.5*10-6 rad for the projectile scattering angle, was obtained by intersecting a well collimated O7+ beam with a target of a supersonic He jet from a pre-cooled gas and by measuring the recoil-ion transverse momentum. For the single capture reaction, information on the n-value of the electron final state in O6+ (1snl) is obtained from the longitudinal momentum of the recoil ions. In pure single-electron capture, the dominant contributions to capture were found to be those from the n=4 and higher states, whereas single capture accompanied by the ionization of the second target electron mainly populates n=2 to n=4 states. Furthermore, the measured transverse momentum distribution differs significantly between pure single capture and capture with simultaneous ionization. The measured data for the pure capture process compare favourably with theoretical results based on a molecular-state expansion method. Other experimental data are discussed in terms of the classical overbarrier model.

Relativistic binary-encounter electrons produced in very fast collisions of bare and H-like Ar with carbon foils are studied as a function of laboratory frame emission angle. It is found that the velocity of the binary-encounter peak is consistent with a relativistic billiard ball model. The cross section for binary-encounter electron production is not in good agreement with a simple Rutherford scattering model. It is also found that the ratio of H-like to bare projectile cross sections is 1 at 0 degrees and becomes less than 1 at large emission angles.

We have used the technique of beam-foil spectroscopy to investigate transition probabilities for Na-like Nb 30+ and Mg-like Nb 29+ . In the former case the lifetimes of the 3 p 2 P 1 2 , 3 2 levels were determined using the ANDC method of cascade correction. For the Mg-like ion we have studied the decay of the 3s3p 3 P 1 level which gives rise to a spin-forbidden transition to the 3s 2 1 S 0 ground term.

Projectile {ital K}{alpha} satellite and hypersatellite x-ray yields were measured in collisions of Ar ions with energies of 43, 52, 65, 80, 95, and 300 MeV with targets of C, Mg, Al, Ti, V, Cr, Fe, Co, Ni, Cu, Zn, Y, Nb, Mo, Sn, Nd, Tb, Ho, Ta, and W with atomic number {ital Z}{sub {ital t}}=6--74. The intensity ratio of hypersatellite to satellite lines is reported as functions of the target atomic number {ital Z}{sub {ital t}} and incident energy {ital E}{sub {ital p}}. The vacancy-sharing model was found to predict the {ital Z}{sub {ital t}} dependence of the intensity ratio at 43 MeV in near symmetric collisions. At energies above 80 MeV, the direct Coulomb processes, exspecially the electron-capture processes, determine the {ital Z}{sub {ital t}} dependence. Average {ital L}-vacancy probabilities are reported for projectiles at energies of 43--95 MeV that acquire single and double {ital K} vacancies in the targets.

Selective production of the doubly excited state in 464 MeV/u He-like Ar${}^{16+}$ ions was accomplished using three-dimensional resonant coherent excitation in a thin foil of silicon crystal. Through a coherent interaction with the periodic crystal field, the Ar${}^{16+}$ ions were resonantly excited sequentially from the ground state to the $1s2p$ (${}^{1}\phantom{\rule{-0.16em}{0ex}}P$) state and then $2{p}^{2}$ (${}^{1}\phantom{\rule{-0.16em}{0ex}}D$) state in a way analogous to two-color x-ray laser excitation. The periodic crystal fields of 10${}^{11}$ V/m in the projectile's frame are equivalent to the fields generated by x-ray lasers with photon energies of 3139.55 and 3286.95 eV and an energy flux of 10${}^{16}$ W/cm${}^{2}$. We confirmed the doubly excited state formation through observation of the subsequent collisional ionization, Auger ionization, and radiative deexcitation.

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. §

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.

In 89-MeV Sc{sup 8+}+He collisions, the light target atom He was used to ionize selectively the 2{ital p} shell of the scandium projectile. The subsequent {ital L}-shell Auger emission from Mg-like Sc{sup 9+} was measured with high resolution using the method of zero-degree Auger spectroscopy. The spectra are dominated by three peak groups that are attributed to transitions from the various initial states belonging to the configuration 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 5}3{ital s}{sup 2}3{ital p} to the final states 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital s} {sup 2}{ital S}, 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital p} {sup 2}{ital P}, and 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital d} {sup 2}{ital D}. The {sup 2}{ital P}{sub 1/2-}{sup 2}{ital P}{sub 3/2} fine-structure splitting was resolved for the final configuration 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital p}. The branching ratio for the transition to 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital d} {sup 2}{ital D}, which involves three electrons and, thus, must be ascribed to correlation, is compared to earlier results for the isoelectronic ions Al{sup +} and Ar{sup 6+}. Good agreement between observed and calculated branching ratios to the three final states is obtained by including onlymore » correlation in the initial state. A discrepancy for the branching to the 1{ital s}{sup 2}2{ital s}{sup 2}2{ital p}{sup 6}3{ital d} {sup 2}{ital D} term, which was observed already in the earlier investigation of Ar{sup 6+}, has been removed by including correlation in the {ital n}=2 shell in addition to the correlation in the {ital n}=3 shell, which was the only correlation introduced previously.« less

Singly excited states of sodiumlike argon and sulfur have been investigated by means of high-resolution 0{degree} Auger spectroscopy at high projectile energies. The Auger-electron spectrum is due to the decay of states populated by monopole, dipole, and quadrupole excitation of the 2{ital p} and 2{ital s} electrons. Collision strengths calculated by means of the configuration-interaction Hartree-Fock program by Cowan ({ital The} {ital Theory} {ital of} {ital Atomic} {ital Structure} {ital and} {ital Spectra} (University of California Press, Berkeley, 1981)) in the plane-wave Born approximation (PWBA) have been used to describe the relative intensities found in the measured spectrum. The intensities due to monopole excitation are significantly higher than the prediction by PWBA for a Coulomb perturbation potential. The structure of the emitted electron spectrum is found to be significantly influenced by the configuration interaction.

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.

Electrons emitted from projectile ions were measured with high resolution in collisions of 64 MeV S 12+ ions with He atoms and C foils by 0° electron spectroscopy. A series of intense lines have been observed, which are attributed to the Coster-Kronig transitions of 1s 2 2p nl -1s 2 2sϵ l' with n = 9 to 19. The angular-momentum ( l ) distribution of ions in the autoionizing states of n = 9 has been obtained and evidence for high l enhancement has been found in C-foil targets.

The radiation effect on the lattice structure of single-crystal austemtic stainless steel SUS310S under He ion bombardment was studied. The He+ ions, with an energy of 1.7 MeV, were incident along the 〈100〉, 〈110〉 or 〈111〉 axes of the specimen. constituent elements induced by He ions as well as Rutherford-backscattered He ions were measured. The lattice location of the alloying and impurity atoms, and their disordering caused by the He irradiation were investigated. It was shown that aligned X-ray yields in the angular scans increase with the irradiation dose except for P atoms, and the degree of the increase depends very much on the crystallographic orientation and the constituent elements. Some of the impurity P atoms were found to be situated at the body-centered site of the fcc crystal and to be displaced from this site under He ion irradiation.

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.

The doubly differential cross sections (DDCS) of double electron capture in collisions of slow ${\mathrm{C}}^{4+}$ with He were measured in the energy range of 240, 320, and $440\phantom{\rule{0.3em}{0ex}}\mathrm{eV}$ (in laboratory frame) using a crossed-beam apparatus and represented as a two-dimensional contour map. The double-electron capture into the ${\mathrm{C}}^{2+}(1{s}^{2}\phantom{\rule{0.2em}{0ex}}2{s}^{2}^{1}S)$ state was found to be dominant in the present energy range. The St\"uckelberg oscillation structures, which result from interference among two different paths on the interaction potential curves, were clearly observed in the DDCS at the present low impact energies. The differential cross sections were also calculated in an ab initio molecular orbital framework for ${(\mathrm{C}\mathrm{He})}^{4+}$, and show a good agreement with the present experimental results.

We report on the selective production of the 2s metastable state of 390-MeV u−1 H-like Ar17+ ions by the resonant coherent excitation (RCE). The RCE to the 2s state was achieved by using Stark mixing of n = 2 states under planar channeling conditions in a 1-m thick Si crystal. The population of the 2s state was quantitatively estimated from the ionization probability in a stripper foil installed 50 mm downstream of the crystal. The 2s population was found to be 0.05 of the total number of Ar17+ ions at the stripper. The result is in good agreement with a theoretical calculation performed with the density matrix approach.

Radioactive beryllium isotope ions ($^{7}\mathrm{Be}^{+}$ and $^{10}\mathrm{Be}^{+}$) that are provided by a projectile fragment separator with $\ensuremath{\approx}1\phantom{\rule{0.3em}{0ex}}\mathrm{GeV}$ beams, as well as stable isotope ions $(^{9}\mathrm{Be}^{+})$ are stored and laser cooled in an online ion trap. Their absolute transition energies of the $2s\phantom{\rule{0.2em}{0ex}}^{2}S_{1∕2}\ensuremath{\rightarrow}2p\phantom{\rule{0.2em}{0ex}}^{2}P_{3∕2}$ transition were measured with an accuracy of $\ensuremath{\sim}{10}^{\ensuremath{-}8}$. In this way isotope shifts of beryllium ions were obtained and the differential mass polarization parameter $\ensuremath{\kappa}=\ensuremath{-}0.286 41(70)\phantom{\rule{0.3em}{0ex}}\mathrm{a.u.}$ as well as the $2s\phantom{\rule{0.2em}{0ex}}^{2}S\ensuremath{\rightarrow}2p\phantom{\rule{0.2em}{0ex}}^{2}P$ transition energy of an infinitely heavy beryllium ion $h{\ensuremath{\nu}}^{\ensuremath{\infty}}=0.145 524 290(42)\phantom{\rule{0.3em}{0ex}}\mathrm{a.u.}$ were determined for the first time.

Beam-foil spectroscopy techniques have been used to study intercombination transitions in Be-like Fe22+ and B-like Fe21+. The method of time delayed spectroscopy was used to identify the Be-like 2s2 1S0-2s2p 3P1 and B-like 2s22p 2P3/2-2s2p2 4P5/2 transitions. Intensity decay curves for these transitions were recorded and level lifetimes were obtained. The latter were found to be 17.5 ± 1.5 ns for the Be-like 2s2p 3P1 level and 14.8 ± 1.0 ns for the B-like 2s2p2 4P5/2 level.

Projectile Kα satellite and hypersatellite X-ray yields are measured in collisions of Ar ions with energies of 43–95 MeV with solid targets, ZT = 6–74. These high resolution X-ray measurements are analyzed using a statistical model with theoretical fluorescence yields to obtain the average probability of ionization of 2s and 2p subshells. Comparison of the measured relative intensities of Kα satellites with the best theoretical fits are presented.

Although the projectile fragment separator (RIPS) at the RIKEN accelerator facility (RARF) provides wide variety of energetic radioactive beams, it is not adequate for low energy beam experiments such as precision spectroscopy of trapped ions. Aiming for an efficient deceleration and cooling of energetic radioactive ions, the development of an rf ion guide system which comprises a large He gas cell and an rf funnel structure in the cell is under progress. A proof of the principle (pop) machine has been successfully tested on-line for collection of 70-MeV/u 8Li ions. A compact gas cell of 70 cm in length and 10 cm in diameter with a He gas pressure of 30 Torr was placed after a variable wedge shaped energy degrader. The ions were stopped in the gas and were transported by a superposition of dc and rf electric field toward a small exit hole. The overall efficiency was 10−4 which can be separated into a gas stopping efficiency of 0.43% and an ion-guide efficiency of 2.4%. The former is limited by the volume ...

An extremely-thin Germanium crystal (0.8 μm-thick) has been firstly exploited in the resonant coherent excitation (RCE) experiment. The 460 MeV/u H-like Fe25+ ions were incident on the Ge crystal under the (220) planar channeling as well as non-channeling conditions. The RCE from 1s to 2p1/2 and 2p3/2 states were successfully observed as an enhancement of the x-ray fluorescence.

We studied the anisotropy of Ly-α x-rays from H-like Ar17+ ions excited by polarization-controlled resonant coherent excitation. The effects of fine-structure depolarization on the 2p1/2 and 2p3/2 states were experimentally demonstrated as a reduction in anisotropy of decay radiation.

We demonstrate the alignment of H-like and He-like heavy ions by three-dimensional resonant coherent excitation in a thin crystalline target. The projectile ions experienced a linearly polarized oscillating field in a crystal and were excited to a specific magnetic substate, forming the aligned 2P state. We prepared the different directions of the aligned states and observed the anisotropy of deexcitation x-ray emission, which was in good agreement with theoretical estimates.

We exploited the double resonance technique in three-dimensional resonant coherent excitation to the production of hollow He-like and Li-like heavy ions. The two K-shell electron were sequentially excited to the L-shell using two frequency components of the oscillating fields arising from the different arrays of atomic planes in a Si crystal.

Convoy electrons emitted from 416 MeV/u heliumlike Ar16+ ions excited by three-dimensional resonant coherent excitation (3D-RCE) have been explored. The 1s electron in the ground state was excited to the 2p state by a periodic crystal field during the passage through a Si crystal and released into the continuum by collisions with target atoms to form a cusp-shaped peak in the energy distribution, referred to as convoy electron. Under the resonance condition, we found not only enhancement of the convoy electron yield but also significant narrowing in the energy distribution, reflecting the initial bound state momentum distribution of the excited ions. This suggests that RCE is well-suited to study fast ion collisions involving the specific excited state.

We investigated resonant coherent excitation (RCE) of 445 MeV/u Li-like Ar15+ under the planar channeling and non-channeling conditions. The K-shell and L-shell excitations are observed as decreases in the survival fraction of the Ar15+ ions after passing through a thin Si crystal. RCE under the planar channeling condition provides the opportunity to study a strong static Stark effect on the Li-like system with K-shell or L-shell vacancy. Under the non-channeling conditions, the observed excitation energies and the reported theoretical calculations were in reasonable agreement.

Slow radioactive ion beams have been produced with an overall efficiency of 4% by thermalizing energetic ions produced by a projectile fragment separator in a He-gas cell and guiding them to a vacuum vessel by dc and rf fields. Space charge was observed to have a limiting effect. Since the ionization of He atoms by energetic ions creates a region of high space charge, many thermalized ions of interest are pushed toward the walls of the gas cell. Such losses have been investigated for different incoming ion intensities.

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 X-ray spectra emitted during the radiative capture of target electrons into the projectile K shell have been measured under single collision conditions for a He gas target. The experiment was performed for 40–76 MeV F q + ( q = 8,9) and 120–175 MeV Cl q + ( q = 16,17) ions. The centroid energies of the radiative electron capture (K-REC) X-rays have been found to be in good agreement with the calculated ones. It is also confirmed that the widths of the K-REC X-ray distributions for Cl 17+ ion impact are in good agreement with the simple model calculations.

Analytic formulas are given for the total cross sections, σ, for the charge transfer in collisions of H + , H − and H with metal vapors. The cross sections considered are σ 10 , σ 0−1 , σ 1−1 , σ 01 , σ −10 , and σ −11 , where the subscripts represent the initial and the final charge state of the projectile. The functional form of the formulas is a modification of the semiempirical formula proposed by Green and McNeal for σ 10 of H + in gaseous atoms and molecules. Values of adjustable parameters in the formulas have been determined by least-squares fits to a compiled set of experimental data. The root-mean-square deviation of the data from the formula is from 7 to 34% for each type of cross section. The main cause of larger deviations is the discrepancy among the data.

Wavelengths, energy levels, level classifications, oscillator strengths, and radiative transition probabilities for the nickel ions Ni IX to Ni XXVIII are critically reviewed and tabulated. Grotrian diagrams are also presented to provide graphical overviews. The literature has been surveyed to mid-1986.

Charge states and angular distributions of 150 MeV Cl ions have been measured as a function of carbon target thickness (2.5–180 μg/cm 2 ). Evidence for the large shell effect under single collision conditions is found in the thinnest target. Transition energies in highly ionized Cl ions have been measured using a grazing incidence monochromator at the VUV region, and using a crystal spectrometer and a Doppler-tuned spectrometer at the X-ray region. The lifetimes have also been measured using the time of flight technique at the VUV and X-ray regions. Results of measurements are given and some are discussed in comparison with other data.

A Beam-foil study was made on highly ionized chlorine ions. Emission lines in the wavelength region from 170 A to 260 A were observed and most of the lines were due to the 2 s -2 p transitions belonging to Cl XII-Cl XIV. Two lines at ∼180 A and ∼206 A are newly identified as transitions between high n l levels of Cl XV and Cl XIV. The lifetimes of 2 s 2 p 1 P 1 and 2 p 2 1 D 2 levels in Cl XIV were determined from the intensity decay curve of 237.7 Aobtained with time-of-flight technique to be 0.14 nsec and 0.60 nsec, respectively.

Wavelengths, intensities, and classifications for the molybdenum ions Mo VI to Mo XLII are compiled. A short review of the work on each stage of ionization is included. The data are critically evaluated and the best results, in our judgement, are quoted.

The cross-section formula of Flannery (Phys. Rev. A 22, 2408 (1980)) in the semiquantal approximation for the processes referred to in the title is rewritten so as to make it more useful in practice. The formula is shown to be further simplified by taking an average over the azimuthal quantum number of a highly excited hydrogenic atom to be ionized. Numerical applications with use of the Glauber amplitude for the electron-atom inelastic scattering are made to the ionization collisions between two excited hydrogen atoms with simultaneous excitation and deexcitation of one of the atoms. The results are compared with those obtained by using the Born amplitude, and are analyzed in terms of the Glauber generalized oscillator strengths.

An experimental study was made on the production of recoil ions in collisions of C and Ne ions with Ne. Absolute values of the Nei+ recoil ion production cross section sigma i were measured. The plot of sigma i against i shows a shoulder at i=3 and 4 in the Neq+-Ne collisions, which becomes conspicuous at the incident energy of 100 keV amu-1. This phenomenon is ascribed to the contribution of transfer ionisation to the recoil ion production. The net ionisation cross section, sigma += Sigma i i sigma i, was compared with a theoretical prediction based on a classical scaling rule.

An improved impulse approximation is used to investigate the ionization collisions between two excited one-electron atoms at high energies. It is shown that the cross sections can easily be estimated by using the quantities calculated in the case of the collisions between two excited hydrogen atoms.