The surface defect structures which were produced on (100) surfaces by 500eV Ne ion bombardment and subsequent annealing were studied  in situ  by means of low-energy electron diffraction, and X-ray absorption near-edge structure spectroscopy which involved 250 to 800eV synchrotron radiation. Also, X-ray photo-emission spectroscopy was used to characterize the defective layer. Appreciable changes in the X-ray absorption near-edge structure spectra were caused by the defects which were introduced by ion bombardment and annealing. The discrete exciton absorption at 289.0eV was clearly suppressed, even at the lowest ion fluence which was used here (3 x 1014/cm2). No such exciton could be observed after a fluence of 7 x 1014/cm2. However, changes in the multi-maximum resonance absorption structure, between 290 and 310eV, indicated that a loss of long-range order required a fluence of 1015/cm2. The structural changes were also reflected by a transformation, of the gap state absorption which was typical of clean 2 x 1 surfaces, into the * absorption which was typical of amorphous C. The use of X-ray photo-emission spectroscopy showed that the defective layer was about 2nm thick. None of the samples exhibited a detectable transformation from defective layers to graphite; even after annealing them at temperatures of up to 1100C.

L.J.Huang, I.Bello, W.M.Lau, S.T.Lee, P.A.Stevens, B.D.DeVries: Journal of Applied Physics, 1994, 76[11], 7483-6