Electron-stimulated disordering in c(8x2) benzoate/Cu(110): a combined STM, LEED and HREELS study

We demonstrate a novel, negative-ion-mediated, electron-stimulated disordering process in LEED and, at nanoscopic scales, in the STM. Electron-stimulated disordering of the c(8 x 2) benzoate/Cu(110) structure in LEED is reversible, and HREELS shows that it is non-destructive to the adsorbed species. The disordering kinetics in LEED are pseudo first-order above a threshold between 5 and 7 eV with a large cross-section (similar to 10(-16) cm(2)). The threshold correlates with strong negative ion resonance scattering in HREELS centred at 7-8 eV. Defect-controlled kinetics in LEED are observed at 5 eV and correlate with the spatial dependence in the STM disordering, which initiates preferentially at domain boundaries and is inhibited at step edges. Both the STM-and electron-beam-induced disordering are consistent with a negative ion resonance mechanism for efficient energy transfer from the tunnelling/incident electron to adsorbate internal vibrational modes which then relax by excitation of the frustrated translation. The influence of field effects on the potential energy surface is also considered. (C) 1997 Elsevier Science B.V.