A new way to see NMR signals

Nuclear magnetic resonance signals have nearly always been observed in the same way: by measuring magnetically induced voltage changes that occur when atomic nuclei are hit with tuned radio waves. But physicist Michael V. Romalis and coworkers at Princeton University now report a new way under the sun-or at least under a laser beam-to carry out NMR measurements in liquids (Nature 2006, 442, 1021). Nuclear-spin optical rotation (NSOR), the technique they've developed, creates NMR signals by detecting phase shifts induced in a laser beam by nuclear spins as the beam passes through a liquid. The sensitivity is currently several orders of magnitude lower than that of regular NMR, but Romalis and coworkers see ways to overcome this shortcoming. In a commentary, Warren S. Warren of Duke University notes an advantage of NSOR, that it has about 100 times better spatial resolution than conventional NMR. "Bringing the power of modern optics to NMR detection could greatly improve image resolution and perhaps even sensitivity," Warren notes hopefully.