Thiel, Patricia A. and Yates, J. T., Jr. and Weinberg, W. H. (1979) Abstract: Adsorption of oxygen on Rh(111). Journal of Vacuum Science and Technology, 16 (2). pp. 438-439. ISSN 0022-5355 http://resolver.caltech.edu/CaltechAUTHORS:THIjvst79
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The adsorption of oxygen on Rh(111) at approximately 100 K has been studied by thermal desorption mass spectrometry (TDS), Auger electron spectroscopy (AES), and low energy electron diffraction (LEED). Oxygen adsorbs in a disordered state at 100 K and orders irreversibly into an apparent (2 x 2) surface structure upon heating to T ≥ 150 K. The kinetics of this ordering process have been measured by monitoring the intensity of the oxygen (1,1/2bar) LEED beam as a function of time with a Faraday cup collector. The kinetic data fit a model in which the rate of ordering of oxygen atoms is proportional to the square of the concentration of disordered species due to the nature of adparticle interactions in building up an island structure. The kinetic data are shown in Fig 1 for five temperatures at which the ordering was measured, where f(N0) is the integrated form of the kinetic rate law. On the basis of these data, the activation energy for ordering is 13.5±0.5 kcal/mol. This is consistent with values reported for oxygen ordering on Ir(111), 16-19 kcal/mol , and for oxygen migration on Ru, 14 kcal/mol .
|Additional Information:||© 1979 American Vacuum Society. (Received 21 September 1978; accepted 6 October 1978) Research was supported by the Army Research Office under Grant No. DAHC04-75-0170. Complete paper to appear in Surface Science. [P.A.T. was a] National Science Foundation Predoctoral Fellow. [J.T.Y., Jr. was a] Sherman Fairchild Distinguished Scholar. [W.H.W. was an] Alfred P. Sloan Foundation Fellow, and a Camille and Henry Dreyfus Foundation Teacher-Scholar.|
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