TIP-INDUCED LIFTING OF THE AU(100) (HEX)-PHASE RECONSTRUCTION IN A LOW-TEMPERATURE ULTRAHIGH-VACUUM SCANNING TUNNELING MICROSCOPE

The clean Au{100} surface is known to be reconstructed, forming a pseu dohexagonal {5 x 27} outermost layer. This structure is observed both in ultrahigh vacuum (UHV) and in the electrochemical environment at po tentials corresponding to small negative surface electronic charges. U sing a UHV scanning tunneling microscope (STM) at 77 K we have observe d that the reconstruction can be lifted at large positive sample biase s, The 20% less dense bulk-terminated surface is produced and the exce ss material appears as irregularly shaped gold clusters. Over a period of a few minutes, however, the surface relaxes back to the pseudo-hex agonal phase, a process that can also be followed with the STM. (C) 19 96 American Vacuum Society.