High-Resolution Scanning Tunneling Microscopy and Spectroscopy Studies of Deoxyribonucleic Acid and Fluorescein Isothiocyanate

By using scanning tunneling microscopy (STM), we obtained submolecular-resolution STM images of a single molecule of DNA labeled with the fluorescent dye fluorescein isothiocyanate (FITC). From the observed bias voltage dependences of the topographic height and I – V characteristics of FITC and the single molecule DNA, we found that FITC and DNA have different electrical properties. This study shows that STM is useful in the analysis of the properties of molecules by the investigation of a single molecule.