We systematically studied a pulsed laser depositing (PLD) scandia thin film
cathode, using AES and XPS to determine its composition and chemical state
s. Favorable activation, emission, and resistance to overheating attained f
or this cathode was related to the surface behavior of Sc, Ba. and W as def
ined by in situ surface analysis and emission measurement. The states and c
hanges of the surface constitution are discussed as a base for modeling cat
hode operation. (C) 1999 Elsevier Science B.V. All rights reserved.