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Spin noise NMR: Two dimensional spectra and non-linear effects

We introduce 2D spin noise NMR methods that exploit H-1 transverse nuclear spin noise for indirect detection. The sensitivity of these experiments depends in an unexpected way on the sin concentration due to non-linear behaviour caused by radiation damping. This non-linearity is also detectable in C-13 noise NMR spectra [1]. In the absence of hyperpolarization spin noise detection may be superior to classical detection schemes for small sample amounts (≤ 10*e8 spins), as estimated using an approach by Sleator and Hahn [2]. While signal power scales with the square of the number of spins for polarization based experiments, it scales linearly for noise detection. Currently experiments with such low spin numbers are not in our experimental reach. Therefore we use large spin number samples and state-of-the art hardware (e.g. cryo-probes) to develop noise detection based experiments, which bear the potential of enhanced sensitivity, once applicable to such low spin numbers. As a proof of principle we present a transverse spin noise detected HMQC experiment. By contrast to the earlier spin noise imaging, which is based on projection-reconstruction [3], then new spectroscopic approach is a form of 2D Fourier transform NMR spectroscopy. References [1] Schlagnitweit, J. ; Müller, N. (2012) The first observation of Carbon-13 spin noise spectra, J. Magn. Reson. 224, 78-81. [2] Sleator, T. ; Hahn, E. L. ; Hilbert, C. ; Clarke, J. (1987) Phys. Rev. B 36, 1969-1981. [3] Müller, N. ; Jerschow, A. (2006) Proc. Nat. Acad. Sci. USA 103, 6790-6792.

spin noise; NMR

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