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 dis ordering process in LEED and, at nanoscopic scales, in the STM. Electr on-stimulated disordering of the c(8 x 2) benzoate/Cu(110) structure i n LEED is reversible, and HREELS shows that it is non-destructive to t he 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 nega tive ion resonance scattering in HREELS centred at 7-8 eV. Defect-cont rolled kinetics in LEED are observed at 5 eV and correlate with the sp atial dependence in the STM disordering, which initiates preferentiall y at domain boundaries and is inhibited at step edges. Both the STM-an d 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 fi eld effects on the potential energy surface is also considered. (C) 19 97 Elsevier Science B.V.