HIGH COVERAGES AND SUBSURFACE PENETRATION OF OXYGEN ON RU(001)

Interaction of NO2, an effective source of atomic oxygen, with a Ru(001) single crystal face was studied at substrate temperatures 400-800 K. We present thermal desorption spectroscopy data indicating that up to 40 oxygen monolayers can be accommodated within the surface and subsurface regions. Once oxygen penetrates below the surface, fragments containing Ru atoms (RuO(x), x = 0-3) are detected during desorption and O2 desorbs with near-zero-order kinetics. We briefly discuss these experimental results in terms of a model for subsurface penetration of oxygen on transition metals.