PiFM imaging reveals features that are not clear in topography. Given the height of the bacteriophage M13 (3-4 nm), a single bacteriophage may have been imaged at 1720 cm−1 (C=O) and 1667 cm−1 (amide I) via PiFM.
Filamentous Bacteriophage M13 and Plasmid DNA pUC19