NOON states in star-topology spin-systems: Applications in diffusion studies and RF inhomogeneity mapping

The NOON state is a special multiple quantum coherence that can be prepared easily using a star-topology spin-system. In this Letter we describe two important applications of such systems: (i) measuring translational diffusion constants in liquids and (ii) quantitative characterization of radio-frequency (RF) inhomogeneity of NMR probes. When compared with the standard single quantum method, the NOON state method requires shorter diffusion delays or weaker pulsed-field-gradients. Similarly, Torrey oscillations with NOON states decay at a faster rate than that of single quantum coherences and allow accurate characterization of RF inhomogeneity at higher RF powers.