Showing papers by "Wonyong Choi published in 1990"

Low Energy Ion-Surface Reactor

Abstract: Ion-surface collision studies at low kinetic energies (1-100 eV) provide a unique opportunity for investigating reactions and collision dynamics at surfaces. A special ion optics system for generating an energy- and mass-selected ion beam of this energy is designed and constructed. An ultrahigh vacuum (UHV) reaction chamber, in which the ions generated from the beamline collide with a solid surface, is equipped with Auger electron spectroscopy (AES) and thermal desorption spectrometry (TDS) as in-situ surface analytical tools. The resulting beam from the system has the following characteristics : ion current of 5-50 nA, energy spread and unit mass resolution below 20 amu. The performance of the instrument is illustrated with data representing the implantation behavior of into a graphite (0001) surface.

Ion and X-ray induced decomposition of alkali halates. A comparative study of the radiation induced reaction paths

Abstract: Decomposition reactions of NaClO3, KClO3, and KIO4 induced by 3 keV Ar+ ions and 1254 eV X-rays are investigated by X-ray photoelectron spectroscopy (XPS). The reactions lead to the formation of binary halides with preferential losses of oxygen. The decomposition pattern, monitored at the various stages of reaction, indicates almost direct changeover to the final products with only a few intermediate species formed. Product abundancies are compared for the ion, X-ray, and electron induced reactions and discussed in relation to the various radiation induced reaction mechanisms.