Chemical fingerprintin with scanning tunne o

sity ty o d fo 29 Scanning tunneling spectroscopy (STS) based on scanning tunneling microscopy (STM) makes it possible to map the local electronic Atomic-scale chemical analysis has been a long-standing where dual bias imaging was needed to distinguish the tion of the electronic states makes chemical recognition possible for halogen adatoms on Si(001). To demonstrate this, we measured current–voltage spectra throughout the scanned area to obtain three-dimensional maps of the local density of states (LDOS). We exploit the fact that the en-ergy levels depend on the adatom species and the substrate