Hydrogen atoms cause long-range electronic effects on graphite

We report on long-range electronic effects caused by hydrogen-carbon intera ction at the graphitesurface. Two types of defects could be distinguished w ith a combined mode of scanning tunneling microscopy and atomic force micro scopy: chemisorption of hydrogen on the basal plane of graphite and atomic vacancy formation. Both types show a (root 3 X root 3)R30 degrees superlatt ice in the locll density of states but have a different topographic structu re. The range of modifications in the electronic structure, of fundamental importance for electronic devices based on carbon nanostructures, has been found to be of the order of 20-25 lattice constants.