SCANNING THERMOPOWER MICROSCOPY OF GUANINE MONOLAYERS

Thermally deposited monolayers of the DNA base guanine have been studi ed by scanning tunneling microscopy (STM) and a novel scanning thermop ower microscope (STPM). The STPM signal provides a distinct representa tion of the monolayer lattice not present in the STM signal. The inten sity of the thermopower contrast is dependent on the temperature gradi ent at the tunnel junction. Surface roughness and topographical variat ions of the underlying substrate are not convoluted with the signal du e to the feed-forward acquisition method of this technique. A plausibl e interpretation of the STPM signal and images is proposed, and the pr ospects for single molecule differentiation and spectroscopy are discu ssed.