Spin-Noise-Detected Two-Dimensional Fourier-Transform NMR Spectroscopy

Abstract

We introduce two-dimensional NMR spectroscopy detected by recording and processing the noise originating from nuclei that have not been subjected to any radio frequency excitation. The method relies on cross-correlation of two noise blocks that bracket the evolution and mixing periods. While the sensitivity of the experiment is low in conventional NMR setups, spin-noise-detected NMR spectroscopy has great potential for use with extremely small numbers of spins, thereby opening a way to nanoscale multidimensional NMR spectroscopy.

Dependence of NMR noise line shapes on tuning, matching, and transmission line properties

“…One can nowadays easily observe nuclear spin-noise on conventional NMR spectrometers at room temperature using cryogenically cooled probes for a large number (∼10 20 −10 22 ) of proton spins 2,14, and 13 C spin-noise 17 as well as heteronuclear 2D NMR with spin noise detection 18 were also recently demonstrated. Even two-dimensional spin-noise spectra were acquired recently from a macroscopic sample.…”

Nuclear spin noise in NMR revisited

“…Also, the appearance of cold-probes with very large quality factors has facilitated the detection of nuclear spin noise. It has, for instance, allowed the direct acquisition of images without RF excitations [23] or the detection of thermally polarized 13 C nuclear spin noise [24]; even 2D-NMR spectra based on spin-noise detection scheme have been reported [25]. Nevertheless, with consequences on a much broader audience these fundamental studies are mainly put forward problems of tuning of the electronic circuit [26].…”

Nonlinear detection of secondary isotopic chemical shifts in NMR through spin noise

“…This detection principle is known in NMR as nuclear spin noise121314. It has been used previously for optimizing NMR probe sensitivity15161718 and to achieve NMR detection without rf excitation1920 which is useful under high polarization conditions212223. Here, we show that minor components, such as isotopic satellites, in concentrated solution or neat liquids can be more easily and more reliably determined by spin-noise detection than by the usual methods involving rf excitation, in particular when the electronic detection circuit is at lower temperature than the sample.…”