It's an odd way to do chemistry. In a small room off his main lab at Northwestern University, Chad Mirkin sits at a personal computer and types. Next to him on the desktop is a plain-looking analytic instrument. Only this is no ordinary piece of lab equipment. It's an atomic force microscope, or AFM, and it's changing the way scientists interact with matter on the very small scale. This particular version of the AFM, specially modified by Mirkin and his co-workers, is about to perform a feat that just a few years ago would have been unthinkable.

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