SCANNING TUNNELING MICROSCOPY AND TUNNELING SPECTROSCOPY OF TITANIUM BEFORE AND AFTER INVITRO IMMERSION

In an effort to understand the in vivo interactions of titanium and its alloys with a biological environment, surface science methods have been used on specimens retrieved from in vitro and in vivo experiments. A relatively new technique that has the potential to further our knowledge of the oxide-solution interface is scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (TS). This work documents the use of STM/TS in the study of titanium thin films before and after immersion in an in vitro solution. Titanium thin films were fabricated using a procedure which produced an oxide that had minimal contaminants. Half of the thin films were immersed in an electrolyte. STM/TS was performed immediately after the immersion period. Constant current images were obtained. Current-voltage characteristics were recorded at regions of interest. The topography of the nonimmersed films revealed that the surface was qualitatively the same as other sputter deposited metal films. I-V curves showed little spatial variation. The topography of the immersed film showed little change from the nonimmersed ones. However, significant spatial variation of the local electronic structure was noted. This indicates that titanium surface-fluid interactions do not occur uniformly on the film.