Solids Analysis Using Energetic Ion Bombardment and - and Angle-Resolved Distributions of Ejected Neutral Particles.

There has been interest in keV particles for over fifty years. Although the number of applications in this field has continually expanded, the complexity of both experiment and theory has made advances in basic concepts difficult to obtain. This thesis describes how advanced technology in several areas can be used to provide concurrent energy- and angle-resolved neutral (EARN) particle distributions from ion bombarded surfaces. Experimental and theoretical approaches towards understanding the sputtering event are discussed, emphasizing the best methods of determining energy and angular distributions. The EARN detector is described in detail. The ejecting neutrals are ionized in a ribbon-shaped laser beam using multiphoton resonant ionization, an electronic state selective, and therefore atom selective technique. The ions are imaged onto a microchannelplate, and video techniques are used to produce an angular distribution. A pulsed ion beam, laser beam, and pulsed detector are used to extract the velocity and mass of the ejecting particle. Studies in which 5-keV Ar^+ ions are directed normal to polycrystalline surfaces have provided many interesting results. It was found that energy and angular distributions of ejecting particles are not independent. The most probable energy of ejection decreases with increasing polar angle, and the angular distribution narrows as higher kinetic energy particles are sampled, even though angle-integrated energy distributions are quite similar to those reported earlier. Dimer distributions are shown and compared with monomer distributions indicating that changes in initial spatial ejection distributions are one of several reasons why the power law may not work in determining whether recombination has occurred. The ejection of atoms in metastable excited states is also discussed. The ejection of rhodium atoms from clean and oxygen -covered Rh(111) by normally incident 5-keV Ar^+ ions is also discussed. The results show a normal ejection peak at high energies, and compare favorably with classical dynamics calculations for the clean surface. The presence of oxygen on the surface affects both the energy and the angular distributions, particularly at low ejection energies. This thesis provides basic experimental information used to advance our understaning of keV particle bombardment.