Complex ion-distribution induced contrast reversal in STM imaging of DNA

Dong Hee Kim*, Errez Shapir, Hawoong Jeong, Danny Porath, Juyeon Yi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


We study scanning tunneling microscope (STM) measurements of DNA molecules. It is found that the counterions along the DNA induce an attractive potential that modifies the nature of the tunneling current such that contrast inversion emerges in the STM images. By analyzing the current-distance (I-z) dependence, we demonstrate theoretically that the DNA image contrast with respect to the substrate can be reversed by changing the current setting Iset or the bias voltage setting Vset. These findings are consistent with our experimental observations of current and bias voltage dependent contrast changes in direct STM measurements.

Original languageAmerican English
Article number235416
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number23
StatePublished - 2006


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