Reproducibility of O- negative ion emission from C12A7 crystal surface

Reproducibility, stability and oxygen-pressure dependence of O- negative ion emission from a synthesized crystal 12CaO . 7Al(2)O(3) (C12A7) surface have been investigated. We found the continuous 0 implantation into the C12A7 crystal can be simply realized by supplying electron and oxygen on the Au-deposited C12A7 surface via electrocatalytic reactions. The O- emission from the consumed C12A7 surface was recovered after the implantation operation (O-2: 0.13 Pa: 770degreesC) for 30 minutes. In contrast, the implantation influence on electron emission is negligible. The O emission intensity is nearly constant in the O-2 pressure lower than 1 x 10(-3) Pa. The O- implantation mechanism will be addressed.