Spatially resolved spectroscopy using tapered stripline NMR

•New method to produce arbitrary shape B1 profiles, including linear gradients.•Full characterization by numerical and spatially resolved nutation mapping.•Application to spatially resolved spectroscopy without switching gradients.•Application to fast in-situ reaction monitoring.•Application to compensate spectral resolution in inhomogeneous magnetic field.

Magnetic field B0 gradients are essential in modern Nuclear Magnetic Resonance spectroscopy and imaging. Although RF/B1 gradients can be used to fulfill a similar role, this is not used in common practice because of practical limitations in the design of B1 gradient coils. Here we present a new method to create B1 gradients using stripline RF coils. The conductor-width of a stripline NMR chip and the strength of its radiofrequency field are correlated, so a stripline chip can be tapered to produce any arbitrary shaped B1 field gradient. Here we show the characterization of this tapered stripline configuration and demonstrate three applications: magnetic resonance imaging on samples with nL-μL volumes, reaction monitoring of fast chemical reactions (10−2-101 s) and the compensation of B0 field gradients to obtain high-resolution spectra in inhomogeneous magnetic fields.

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