Oxygen chemisorption and oxide film growth on Ni{100}, {110}, and {111}: Sticking probabilities and microcalorimetric adsorption heats

摘要: Using single-crystal adsorption calorimetry, heat data have been measured for the of oxygen on three low-index planes Ni at 300 K along with corresponding sticking probabilities. New are presented coadsorbed potassium each plane, and temperature-dependent O2/Ni{100}. The initial heats Ni{100}, {110}, {111} 550, 475, 440 kJ (mol O2)−1, respectively, K, is found to drop rapidly coverage in chemisorption regime, indicating strong interadsorbate interactions. However, this rapid decline not seen potassium, a difference discussed both terms electron availability coadsorbate attractions. integral oxide film formation 220, 290, 320 kJ mol−1, respectively. Corresponding probability measurements show values, all less than unity, 0.63, 0.78, just 0.23, again {100}, surfaces that order. dependence consistent case passivating four layers thick. Comparable Ni{100} obtained using pyroelectric detector gave good agreement conventional results K. At 410 however, heat-coverage curve was flat up 0.25 monolayers. Data were also 90 Analysis Monte Carlo simulation curves indicates large room temperature local second-nearest neighbor adatom–adatom repulsion rather long-range electronic effect.