NMR Force Microscopy of Ammonium Sulfate with 12 μm Resolution

Abstract

Position-dependent force-detected NMR measurements on a 25x15x7 μm 3 single crystal of ammonium sulfate (NH 4 ) 2 SO 4 were performed at room temperature in a sample-on-oscillator configuration. Force signals were detected with 12 μm resolution in a one-dimensional scan. Measurements of NMR relaxation times T 2 * = 1.5 ± 0.3 μs, T 2 = 44 ± 2 μs, and T 1 = 5.6 ± 0.7 s were obtained in an 8-T magnetic field, revealing an unexpected frequency-dependent fluctuation spectrum at room temperature.