Thermal Desorption of Potassium from Clean and Sulfur Covered Nickel
R. Błaszczyszyn, M. Błaszczyszynowa and W. Gubernator
Institute of Experimental Physics, University of Wrocław, Pl. Maxa Borna 9, 50-204 Wrocław, Poland
Received: May 31, 1995; revised version: July 18, 1995
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Activation energy for thermal desorption of potassium from clean and sulfur covered surfaces of nickel was determined by means of the field emis­sion method. For the low potassium coverage limit (ΘK ≈ 0.02) the desorp­tion was detected from the whole emitter surface in the temperature range of 825-1000 K for the atoms and of 725-825 K for the species of atoms and ions of the potassium. The activation energies of neutral desorption were found to be EaNi = 3.8 eV for the clean nickel and EaS/Ni = 3.0 eV for the sulfur covered nickel, Θs ≈ 0.5. The activation energies for the desorption of the species of atoms and ions increased from Ea+iNi = 2.5 eV for the clean nickel to Ea+iS/Ni = 2.9 eV for the sulfur covered nickel Θs ≈ 0.5. Also, a value of Ea+iS'/Ni = 4.1 eV was found for a higher coverage of sulfur, Θs ≈ 1. The results are discussed in terms of Gurney model.
DOI: 10.12693/APhysPolA.88.1151
PACS numbers: 73.30.+y, 79.60.Dp, 79.90.+b