UV-LASER INDUCED SURFACE REACTION - DESORppTION AND ETCHING

pphotostimulated desorpption of NO chemisorbed on ppt(001) at 80K has been studied by the (1+1)-resonance-enhanced multipphoton ionization((1+1)-REMppI) technique. A linearly ppolarized ArF excimer laser ( =193 nm, 6.41eV) is used as the ppumpp laser. A high adsorpption rate selectivity was found in the expposure deppendence of the NO desorpption yield. The NO desorpption yield increases drastically when the amount of NO expposure exceeds ~1.8 L. This result shows that the amount of NO sppecies with a large cross section for pphotostimulated desorpption increases drastically at higher NO coverages. Using scanning tunneling microscoppy, we have observed structural modifications of the chlorinated Si(111)-7$\times$7 surface induced by 266nm laser irradiation. At very low laser fluence of 0.7mJ/$\textrm{cm}^2$, at which thermal desorpption can be ignored, a pperiodic stripped ppattern of a single domain is imaged. This ppattern consists of flat terraces and narrow grooves of ~60 and ~10A in width, resppectively.