X-Ray Emission from Slow Highly Charged Ar Ions Interacting with a Ge Surface

We have measured K x-ray spectra and yields from Ar17+ ions slowly approaching a single-crystal Ge surface. The yields were measured as a function of the projectile velocity component perpendicular to the surface. From the data a characteristic time of approximately 1 psec was extracted for the in-flight filling above the surface of the Ar K vacancy

Dielectronic Recombination on and Electron-Impact Excitation of Heliumlike Argon

We have measured cross sections for Δn=1 dielectronic recombination (DR) on He-like argon and found good agreement with theoretical calculations based on the Hartree-Fock atomic model. Experimental absolute cross sections were obtained by using the electron-energy dependence of yields of He-like and Li-like argon ions from the Kansas State University electron-beam ion source to measure the ratio of the DR cross section on He-like argon to the electron-impact-ionization cross section of Li-like argon and normalizing to the latter. The K x-ray emission spectra due to Δn=1,2 DR and n=1→2 electron-impact excitation of He-like argon were also observed with a Si(Li) detector placed at 0° relative to the electron-beam direction. By normalizing to the theoretical KLL integrated DR differential cross section, we obtained differential and partial differential DR cross sections and differential electron-impact excitation cross sections. We found good agreement with Hartree-Fock calculations for DR and with distorted-wave calculations for electron-impact excitation

Evidence of Wave-Particle Duality for Single Fast Hydrogen Atoms

We report the direct observation of interference effects in a Young\u27s double-slit experiment where the interfering waves are two spatially separated components of the de Broglie wave of single 1.3 MeV hydrogen atoms formed close to either target nucleus in H++H2 electron-transfer collisions. Quantum interference strongly influences the results even though the hydrogen atoms have a de Broglie wavelength, λdB, as small as 25 fm

State Selective Scattering Angle Dependent Capture Cross Sections Measured by Cold Target Recoil Ion Momentum Spectroscopy

We have developed a new kind of recoil ion momentum spectroscopy technique, using a precooled supersonic gas jet target, to determine state selective, scattering angle dependent cross sections for swift ion-atom collisions ( 0. 25 , ..., , 1 MeV He2+ on He), by measuring the transverse and longitudinal momentum of the recoil ion. A longitudinal momentum resolution of ± 0.13 a. u. was achieved, about a factor of 30 better than ever obtained before, which enables a clear separation of K and L shell capture. In the transverse direction a resolution corresponding to a projectile scattering angle uncertainty of Δ ϑ P = ±1 μ rad was obtained

K X-Ray and Auger Emission from H-like Ar Ions Slowly Approaching a Ge Surface

We have studied K x-ray and Auger emission from Ar17+ ions interacting with a Ge surface. The x-ray yields were studied as a function of the vertical projectile velocity with respect to the surface. © 1991 Springer-Verlag

Recent Experiments on the KSU EBIS

The KSU EBIS operates presently for the production of external ion beams at energies up to q x 4 keV and as an ion trap for electron-ion collisions with electron energies below 6 keV. Measurements of dielectronic recombination with heliumlike Ar have been carried out with the source using both the charge state equilibrium of the electronically monoenergetic plasma and the yield of X-rays from the source interior. These experiments yield information on both the state of the source plasma and the relevant ionization and recombination cross sections. The X-ray data show dielectronic recombination resonances both below and above the n = 1 to 2 excitation thresholds, and may be analyzed to yield an experimental cross section for L shell excitation in heliumlike argon. Extracted beams have been used to measure K X-ray and Auger electron production for Ar17+ on single crystal Ge targets. Results of these experiments and some source characteristics are presented and discussed

Recent Experiments on the KSU CRYEBIS

The CRYEBIS at KSU is in operation since the spring of 1989. The experimental efforts undertaken since then were focused on two projects: In one the interaction of the produced ions with the electron beam in the source is studied. In the second project the ions are extracted from the source and the interaction with a solid surface is investigated. Here we report on first results of these experiments