XPS study on microporous surface composition of microchannel plates

摘要

X-ray photoelectron spectroscopy (XPS) was used to study the microporous surface elements change in content and chemical states of microchannel plates before and after hydrogen reduction. The results show that the oxygen charge states include mixture of bridging oxygen (BO), non-bridging oxygen (NBO), and hydrogen oxide (-OH), and BO is the main charge state, that Si, Pb and Bi are also bonded with F to produce fluoride except bonding with oxygen before hydrogen reduction. After hydrogen reduction, the binding state of O and Si unchanged. The [BO] and [NBO] decrease, and [OH] increases obviously. Si fluoride reacts with H_2O and produces amounts of ≡Si-O- at high temperature. The lead exists in mixture of Pb° and Pb~(2+), and the Bi mainly exists in bond of Bi° in surface region of the reduced samples. The signals of K2p and Nals emerged again in the reduced samples. It is the change in content and chemical states of microchannel plates after hydrogen reducing processing that the secondary electron emission yield after reduction is 1.5 times higher than that of samples before reduction, and the bulk resistivity obviously drops by 3～4 order.