The adsorption of CO on Pd(111) has been studied with scanning tunneling mi
croscopy in the very low coverage regime. Isolated CO molecules were imaged
with two different corrugations of similar to 0.25 Angstrom and similar to
0.15 Angstrom, which are attributed to adsorption of the hcp and fee hollo
w sites. Total energy calculations reveal that these two sites are the most
favorable ones. Calculated image profiles using the ESQC method agree well
with the experimental corrugations. (C) 2000 Elsevier Science B.V. All rig
hts reserved.