HYDROGEN AND OXYGEN NEGATIVE-ION PRODUCTION BY SURFACE-IONIZATION USING DIAMOND SURFACES

In this paper we report on the first observation of the formation of n egatively charged ions upon reflection from a diamond surface. Positiv e H-2 and O-2 ions are scattered at small angles of incidence from a p olycrystalline diamond surface. Charge exchange is observed yielding n eutral particles and negatively charged ions. The negative ion fractio ns in the reflected particle flux are 5.5% and 29% for hydrogen and ox ygen, respectively. These high negative ion yields are maintained in a moderate vacuum environment (10(-7) mbar) over weeks without further periodic reconditioning of the surface. (C) 1997 Elsevier Science B.V.