Scanning tunneling microscopy (STM) has been used to study the surface of ${\mathrm{C}}_6$Li as a stage-1 donor graphite intercalation compound from a submicrometer down to the atomic scale. Ordered superlattices commensurate as well as incommensurate with the graphite lattice have been observed. The measured STM corrugation at small bias voltage (<200 mV) has been found to be similar to graphite whereas at larger bias voltage a strong decrease of the corrugation was observed. This experimental result is compared with recent theoretical predictions.

• Received 3 February 1989

DOI:https://doi.org/10.1103/PhysRevB.39.11135