ELECTRON-STIMULATED DESORPTION OF ATOMIC OXYGEN FROM POLYCRYSTALLINE AG

Emission of neutral oxygen atoms from an oxygen-charged polycrystalline Ag wire has been examined by using electron-stimulated desorption (ESD0 in conjunction with threshold ionization detection (appearance potential). A quadrupole mass spectrometer was used to detect the neutral oxygen atoms, but the ionizer was operated in the appearance potential mode to make it possible to distinguish the oxygen atoms from products formed by collision of the oxygen atoms with the walls. Loss of the reactive oxygen atoms was also minimized by enclosing the ESD chamber in fused silica. With a primary beam energy of 100 eV, the ESD cross section for oxygen atom desorption was found to be 7 multiplied by 10** minus ** 1**9 cm**2 at 100 degree C, and an ESD threshold was found to exist below 34 eV.