Photoelectronic scoping of adatoms, atomic vacancies, and the outermost   layer of a surface
  An effective yet simple means disclosed herewith has allowed us to gain the atomistic, local, and quantitative information of bonds and electrons at sites surrounding undercoordinated atoms, complementing the scanning tunneling microscopy/spectroscopy and photoelectron spectroscopy (XPS). Examining Rh and Pt surfaces with and without adatoms and graphite surface with and without atomic vacancies, we confirmed that: i) bonds between undercoordinated atoms become shorter and stronger; ii) subjective polarization happens to the valence electrons of defects or adatoms by the densely entrapped bonding electrons, which in turn screens and splits the crystal field and hence the core band of the specimen. 
Yan Wang, Yanguang Nie, Jisheng Pan, Wei Qin, Zhaofeng Zhou, Weitao   Zheng, Chang Q. Sun
cond-mat.mes-hall