ABSTRACT
In this work we investigate some of the key factors in simultaneously recorded scanning tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM) images of the TiO(2)(110) surface, particularly the role of tip size and orientation in the obtained contrast pattern, and the importance of tip-surface relaxations and surface impurities in measured currents. We show that, while using multi-channel scanning modes provides an increase in physical data from a given measurement and greatly aids in interpretation, it also demands much greater rigor in simulations to provide a complete comparison.
ABSTRACT
From an interplay between simultaneously recorded noncontact atomic force microscopy and scanning tunneling microscopy images and simulations based on density functional theory, we reveal the location of single hydrogen species in the surface and subsurface layers of rutile TiO2. Subsurface hydrogen atoms (H(sub)) are found to reside in a stable interstitial site as subsurface OH groups detectable in scanning tunneling microscopy as a characteristic electronic state but imperceptible to atomic force microscopy. The combined atomic force microscopy, scanning tunneling microscopy, and density functional theory study demonstrates a general scheme to reveal near surface defects and interstitials in poorly conducting materials.
