Atomic Force Microscope Takes Pictures of Chemical Bonds

Atomic force microscopy (AFM) is a imaging technique that works on a completely different principle from optical microscopes. Instead of magnifying light waves, an AFM device passes a needle-like probe over a surface and constructs an image of the surface based on subtle variations in the strength of probe-surface forces.

AFM and related imaging techniques generated lots of buzz in the 90’s by providing images of molecules, even individual atoms, on surfaces. AFM has returned to the front page with even higher-resolution images that track the pathways electrons take in  chemical bonds, even hydrogen bonds. Compare the white tracks in the AFM image (left) with the pattern of covalent and hydrogen bonds expected from the structural formulas (right) (click image to enlarge).

from Science magazineFor an easily digested description, see “Hydrogen Bonds Visualized” in C&ENews, 30 Sept, 2013. Or check out the original research article by J. Zhang et al, “Real-Space Identification of Intermolecular Bonding with Atomic Force Microscopy” (Science, 26 Sept 2013, DOI: 10.1126/science.1242603).

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