The secondary electron yield of TiZr and TiZrV non-evaporable getter thin film coatings

The secondary electron yield (SEY) of two different non-evaporable getter ( NEG) samples has been measured 'as received' and after thermal treatment. T he investigated NEGs are TiZr and TiZrV thin film coatings of 1 mum thickne ss, which are sputter deposited onto copper substrates. The maximum SEY del ta (max) of the air exposed TiZr and TiZrV coating decreases from above 2.0 to below 1.1 during a 2h heat treatment at 250 and 200 degreesC, respectiv ely. Saturating an activated TiZrV surface under vacuum with the gases typically present in ultra-high vacuum systems increases delta (max) by about 0.1. C hanges in elemental surface composition during the applied heat treatments: were monitored by Auger electron spectroscopy (AES). After activation carb on, oxygen and chlorine were detected on the NEG surfaces. The potential of AES for detecting the surface modifications which cause the reduction of S E emission during the applied heat treatments is critically discussed. (C) 2001 Elsevier Science B.V. All rights reserved.