| Abstract: | Graphene is known for its many superlatives – strongest, most impermable, most conducting, highest thermal conductivity, etc. But some of its notable properties disappear in the presence of defects. I will discuss the effect of single atom vacancies on graphene's magnetic and electronic properties as revealed by scanning tunneling microscopy and spectroscopy. Topics will include Kondo screening of the vacancy magneic moment and observation of the ultra-relativistic analogue of atomic collapse at a supercritically charged vacancy. |