Enhancement of magnetization transfer effects by inter-molecular multiple quantum filtered NMR

Uzi Eliav^a and Gil Navon^{, a,
a}School of Chemistry, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
Received 10 May 2007. Available online 28 September 2007.

Abstract

There are a number of methods that give MRI contrasts based on changes of the water M_z magnetization as a result of magnetization transfer to macromolecules. In the present work we report that a combination of these methods with inter-molecular multiple quantum coherences (iMQC) gives enhanced effects. For the magnetization transfer contrast (MTC) method an effect of (M_z/M₀) becomes (M_z/M₀)^l where l is the rank of the tensors constituting the iMQC. A similar trend was found upon combining iMQC with the Goldman–Shen experiment. It is pointed out that the method is general for all magnetization transfer methods, including the nuclear Overhauser effect.

Keywords: iMQC; Intermolecular dipolar interaction; Magnetization transfer; MTC; Goldman–Shen

NMR Time Reversal as a Probe of Incipient Turbulent Spin Dynamics

NMR Time Reversal as a Probe of Incipient Turbulent Spin Dynamics
M. E. Hayden,1 E. Baudin,2 G. Tastevin,2 and P. J. Nacher2

1Physics Department, Simon Fraser University, 8888 University Drive, Burnaby BC, Canada V5A 1S6
2Laboratoire Kastler Brossel, Ecole Normale Supérieure; CNRS; UPMC; 24 rue Lhomond, F75005 Paris, France
Phys. Rev. Lett. 99, 137602 (2007)
(Received 23 April 2007; published 27 September 2007)

We demonstrate time reversal of nuclear spin dynamics in highly magnetized dilute liquid ³He-⁴He mixtures through effective inversion of long-range dipolar interactions. These experiments, which involve using magic sandwich NMR pulse sequences to generate spin echoes, probe the spatiotemporal development of turbulent spin dynamics and promise to serve as a versatile tool for the study and control of dynamic magnetization instabilities. We also show that a repeated magic sandwich pulse sequence can be used to dynamically stabilize modes of nuclear precession that are otherwise intrinsically unstable. To date, we have extended the effective precession lifetimes of our magnetized samples by more than three orders of magnitude.

(Thanks to Louis Bouchard for sending...Curt)