EXTENDED MODIFICATIONS OF ELECTRONIC-STRUCTURES CAUSED BY DEFECTS - SCANNING-TUNNELING-MICROSCOPY OF GRAPHITE

Electronic effects from two well-defined defects are identified and me asured using scanning tunneling microscopy on graphite. An atomic vaca ncy on the topmost (0001) plane caused a lowering of apparent z height in a 30 angstrom X 30 angstrom area by approximately 1.5 angstrom. A plane rotation relative to the third surface layer caused a Moire patt ern, with an attenuation along the c axis about 2.6 per monolayer. A ' 'supervacancy'' was imaged due to competition between the above two ef fects. An explanation based on changes in density of states near the F ermi level is proposed.