AI Article Synopsis
- DNA imaging has evolved significantly with advancements in scanning tunneling microscopy (STM), highlighting the issue of negative contrast where DNA appears darker against a metallic background.
- This study investigates contrast inversion in DNA STM imaging through controlled experiments and observations of how DNA's apparent height changes with different imaging bias voltages.
- A model is proposed to explain this contrast inversion, suggesting it results from resonant tunneling through virtual states in the space between the STM tip and the DNA molecule.
Article Abstract
DNA has been at the center of an imaging effort since the invention of the scanning tunneling microscope (STM). In some of the STM imaging reports the molecules appeared with negative contrast, i.e., "submerged" under the metal background and darker. We demonstrate the phenomenon of contrast inversion in DNA STM imaging by controlled and spontaneous contrast inversions and by the dependence of the DNA apparent height with respect to the surface on the imaging bias voltage. Using these characterizations, we formulate a model explaining the above phenomenon by resonant tunneling through virtual states in the vacuum between the STM tip and the DNA molecule.
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| http://dx.doi.org/10.1021/jp052738e | DOI Listing |
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