The secondary-electron yield of air-exposed metal surfaces |
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Authors: | N Hilleret C Scheuerlein M Taborelli |
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Institution: | (1) European Organization for Nuclear Research (CERN), 1211 Geneva 23, Switzerland, CH |
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Abstract: | The secondary-electron-yield (SEY) variation of atomically clean metal surfaces due to air exposure and during subsequent
heat treatments is described. As an example SEY results are presented for the case of a sputter-deposited Nb thin film. Corresponding
variations in the surface chemical composition have been monitored using AES and SSIMS. On the basis of these results, and
of previously obtained SEY results for metals and metal oxides, the origin of the SEY variations is discussed.
The SEY increase, which is generally observed during long-lasting air exposure of clean metals, is mainly caused by the adsorption
of an airborne carbonaceous contamination layer. The estimated value of about three for the maximum SEY of this layer is higher
than that of all pure metals.
Only in some cases can the air-formed oxide contribute to the air-exposure-induced SEY increase, while many oxides have a
lower SEY than their parent metals. From the experimental data it can also be excluded that the SEY increase during air exposure
is mainly due to an increased secondary-electron escape probability.
Received: 17 June 2002 / Accepted: 25 June 2002 / Published online: 15 January 2003
RID="*"
ID="*"Corresponding author. Fax: +41-22/767-9150, Email: Christian.Scheuerlein@cern.ch |
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Keywords: | PACS: 79 20 Hx 82 80 Ms 82 80 Pv 85 25 Am 81 65 Cf |
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