DIFFUSION OF POTASSIUM ON THE W(112) PLANE PREADSORBED BY Ni ATOMS: FIELD EMISSION CURRENT FLUCTUATIONS - AUTOCORRELATION STUDY |
| T. Biernata, R. B³aszczyszyna and Ch. Kleintb aInstitute of Experimental Physics, University of Wroc³aw, Pl. Maxa Borna 9, 50-204 Wroc³aw, Poland bFakultäat für Physik und Geowissenschaften, Universität Leipzig, Linnestr. 5, 7010 Leipzig, Germany |
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| Received: December 11, 2000; in final form May 14, 2001 |
| Diffusion of potassium adsorbate on the W(112) plane with preadsorbed nickel was investigated by means of the autocorrelation function of field emission current fluctuations. A comparison of the experimental autocorrelation function with that of a theoretical calculation by Gesley and Swanson gives the surface diffusion coefficient of potassium. From its temperature dependence the diffusion activation energy at several Ni pre-coverages for a constant potassium coverage (ΘK=0.4) is derived. The dependence of the activation energy for potassium surface diffusion on the nickel coverage - first reduction and then an increase with increasing Ni coverage - is observed. This is in agreement with the results obtained from the spectral analysis of the field emission current fluctuations of the same system. The decrease is understood to be a result of the smoothing effect caused by Ni atoms on the W(112) plane. |
| DOI: 10.12693/APhysPolA.99.665 PACS numbers: 79.70.+q, 68.37.Vj, 68.43.Jk, 05.40.Ca |