The laser annealed Si(111) 1×1 surface with chemisorbed oxygen at submonolayer coverages and its irradiation with a ruby laser has been studied with ultraviolet photoelectron spectroscopy and high-resolution electron-energy-loss spectroscopy. The surface oxide which forms directly upon O2 exposure is found to be similar to that which forms on the Si(111) cleaved 2×1 and the 7×7 reconstructed surfaces. Ruby-laser irradiation converts this surface oxide at submonolayer coverages into clumps of silicon dioxide and regions of clean silicon. Both surface oxides show electronic transitions in the visible and ultraviolet energy region which may be related to known network and point defects in vitreous and crystalline silicon dioxide. © 1986 Springer-Verlag.