Charge transfer between Li ions and Li atoms in the 14-1000-eV energy region

By means of a crossed-beam technique, the absolute cross section for charge transfer between lithium ions and lithium atoms has been measured for incident ions energies ranging from 14 to 1000 eV. The lithium ions are produced thermally in a b-eucryptite source and are accelerated and focused into a ribbon beam in a Peirce gun. The total energy spread of the beam is less than 3% at all energies; mass analysis shows that above 1000 degrees C emitter temperature the impurity ions in the beam are below 0.2%. This ion beam traverses a high-density, collimated lithium vapor beam issuing from an oven. A typical density of neutral lithium atoms in the interaction region is 10(13) atoms/cm(8). The slow ions produced in the charge-transfer interaction are collected on a negatively biased cage surrounding the interaction volume of the two beams. The slow-ion charge-transfer completely accounts for the ion-beam attenuation, thus indicating that all scattered beam ions are collected. The vapor-beam density was determined by condensing the vapor on a cold target, dissolving the metallic lithium thus collected, and titrating the resulting solution. The cross section for charge transfer varies from 240 X 10-(16) cm(2) at 14 eV incident ion energy to 880X10-(16) at 1000 eV, and has the expected energy dependence for resonant charge transfer where in cident ion energy E is in eV and Q is in cm(2).Supported by Advanced Research Project Agency, Project Defender. OH wishes to acknowledge support received from the Office of Naval Research though the U.S. Naval Postgraduate School Research Foundation

Processes of energy deposition by heavy particle impact. Technical report No. 2

Experimental studies of the Li/sup +/ + He interaction have been extended to smaller internuclear separations to clarify a discrepancy between experiment and theory in the elastic cross sections and to observe and measure cross sections for inelastic excitation. For R less than or equal to 0.5 a/sub 0/ the elastic scattering differential cross section is observed to droop far below that expected from a single-state interaction based on ab initio ground-state potentials. In this same region of R both one- and two-electron excitations of He are observed to be strongly excited, and cross sections were measured for each of them. The lowest inelastic channel is an electron-capture state, which is observed indirectly to be strongly populated also. A diabatic correlation diagram is constructed that exhibits the basic interactions responsible for the excitation

Collision Spectroscopy. I. Analysis of the scattering of He+ by Ne and Ar

Experimental data on the differential scattering of He+ by Ne and Ar in the energy range from 10 eV to 100 keV are plotted in a reduced coordinate system suggested by a scaling law for the forward scattering. The resulting curves are used to determine the interaction potential. The repulsive interaction dominating at higher energies shows pronounced shell-structure effects; leading to the deduction of the screening constants for the L and M shells of Ar and for the K and L shells of Ne. At lower energies a polarization attrac­tion appears, allowing deduction of the polarizabilities of Ne and Ar. A simple analytic potential is constructed, including a polarizability term appropriately damped inside the outer shell, which fits the data over the entire range. In addition to the pure elastic scattering, effects of inelastic interactions are diagnosed. A prominent curve crossing is located and the scattering pattern arising from it is interpreted by a semiclassical theory. In collisions with closer encounters, a different type of inelastic. process appears which apparently involves a more intense coupling than the curve crossing and which appears to open up a number of competing inelastic channels.Supported in part by the National Aeronautics and Space Administration and by the U.S. Army Research Offic

Multistage Gun for Production of Low Energy Ion Beams

The article of record as published may be found at http://dx.doi.org/10.1063/1.1720264USDO

Angle- and spin-resolved photoelectron spectroscopy with atoms and molecules

Heinzmann U. Angle- and spin-resolved photoelectron spectroscopy with atoms and molecules. In: Lorents DC, Meyerhof WE, Peterson JR, eds. Proc. of invited papers 14. ICPEAC, Palo Alto (1985), in Electronic and Atomic Collisions. North Holland; 1986: 37