Number 185 (Story #3), June 28, 1994 by Phillip F. Schewe and Ben Stein MAGNETIC RESONANCE FORCE MICROSCOPY represents the attempted marriage of atomic force microscopy (AFM) and nuclear magnetic resonance (NMR) techniques. Scientists at IBM Almaden have devised a microscope which employs a force-sensing cantilever arm, whose minute motions are observed through interferometry, just as in AFM. But in this case the force measured is not the repulsive force between probe and sample but the magnetic force between the sample (mounted on the arm) and a nearby magnet. As in NMR an external radiofrequency coil causes magnetic nuclei in the sample to oscillate, a process that provides information about the composition and distribution of atoms in the sample. So far the device can detect subfemtonewton forces and has a spatial resolution of 2.6 microns in one dimension, much better than with conventional NMR. (D. Rugar et al., Science, 10 June 1994.)