Accession Number : ADA183354

Title :   The Adsorption of H2 and D2 on Fe(110). 1. Helium Scattering as a Probe of Adsorption.

Descriptive Note : Interim rept.,

Corporate Author : RENSSELAER POLYTECHNIC INST TROY NY DEPT OF MATERIALS ENGINEERING

Personal Author(s) : Kurz,E A ; Hudson,J B

PDF Url : ADA183354

Report Date : 30 Jul 1987

Pagination or Media Count : 33

Abstract : Results of thermal energy atom scattering (TEAS) measurements of hydrogen and Deuterium adsorption-desorption kinetics on Iron (110) are presented in detail, with emphasis on the strength and pitfalls inherent in this recently developed technique. It is shown that, for this system, adlayer coverage is directly related to the height of the specularly scattered peak from an incident helium atomic or deuterium molecular beam. The scattered peak height was used to monitor surface concentration as adsorption or desorption occurred, and at equilibrium. Measurements were carried out both at constant temperatures and during temperature programmed desorption. The cross sections for helium scatttering from deuterium and hydrogen on Iron (110) were found to be 3.4 A squared and 3.5 A squared, respectively. The cross section for D2 scattering from adsorbed deuterium on Fe(110) was measured as 11.0 A squared. The initial sticking coefficient and the rate of adsorption were found to be independent of temperature for both H2 and D2. The desorption kinetics were found to be second order, with activation energies of 26.5 kcal/mole (D2) and 25.0 kcal/mole (H2). The isosteric heats of adsorption are 24.7 kcal/mole (D2) and 24.2 kcal/mole (H2).

Descriptors :   *DEUTERIUM, *HELIUM, *HYDROGEN, *ADSORPTION, ACTIVATION ENERGY, ATOMS, COEFFICIENTS, COMPUTER PROGRAMMING, CROSS SECTIONS, DESORPTION, HEIGHT, IRON, KINETICS, PEAK VALUES, PROBES, RATES, SCATTERING, TEMPERATURE, THERMAL RADIATION

Subject Categories : Inorganic Chemistry

Distribution Statement : APPROVED FOR PUBLIC RELEASE