Jeudi 30 janvier 2003
Nuclear magnetic resonance (NMR) has several unique features which distinguish its physics from other forms of spectroscopy. One particularly remarkable aspect of NMR is that the interaction of nuclear spins with the experimental apparatus is usually much stronger than their interactions with the molecular environment. This inversion of the normal spectroscopic situation has some interesting consequences.
In most spectroscopies, selection rules are a consequence of the spatial symmetry of the molecular environment — a feature of the sample which cannot be manipulated easily. In NMR, on the other hand, spectroscopic selection rules may be engineered almost at will by setting up dynamic symmetries of the experimental radio-frequency pulse sequences, and of the motion of the sample in space.
In this talk I will discuss the engineering of spectroscopic selection rules in solid-state NMR and how symmetry-based pulse sequences may be used to investigate molecular structures with high precision.