Invited Paper IPF-MoM3
Pushing Magnetic Resonance Imaging Into the Nanoscale Regime - the Quest for a Molecular Structure Microscope

Monday, October 20, 2008, 9:00 am, Room 312

I describe our effort to extend magnetic resonance imaging (MRI) into the nanometer regime using a technique called magnetic resonance force microscopy (MRFM). MRFM achieves a billion-fold improvement in the sensitivity of magnetic resonance detection by replacing the conventional inductive pickup with ultrasensitive detection of magnetic force. This increase in sensitivity can be harnessed to greatly improve the resolution of magnetic resonance microscopy. In a series of recent experiments at IBM, we have successfully demonstrated 3D magnetic resonance imaging with spatial resolution on the order of 5 nm. The experiment operates in field gradients up to 50 gauss per nanometer (5 million tesla per meter) and makes use of the naturally occurring statistical polarization of nanoscale ensembles of nuclear spins. Understanding the unusual point spread function of MRFM is key to converting the measured 3D force map into a real-space image of the proton distribution in the sample. As a first demonstration of 3D nanoscale MRI, we have imaged individual tobacco mosaic virus particles. The long term goal of this work is to develop a "molecular structure microscope" whereby one could directly image the 3D atomic structure of macromolecules.