Type S and type M impregnated dispenser cathodes were investigated using home-made soft X-ray appearance potential spectrometer （SXAPS）

commercial X-ray photo-electron spectroscopy （XPS） and Auger electron spectroscopy （AES）. The results indicate the presence of considerable difference between type S and type M cathodes. It was found that in activated type M cathode the barium and oxygen were coadsorbed on surface

while in activated type S cathode the surface contained both barium and barium oxide. A new Auger parameter was recommended as a characteristic parameter in determination of the chemical state of barium

including activated dispenser cathodes. The substrate surface of type M cathodes appears to consist of Os/Ru covered with W which has migrated out of the pores. A model surface of monolayer barium on W was used to examine the destructive effect of beam current used in SXAPS. No evident destructive effect was observed.