DRIVEN TUNNELING - NEW METHODS IN NMR-SPECTROSCOPY

Experiments on tunnelling methyl groups at 4 K create localised wavepacket excitations which are either stationary or have a characteristic frequency nu(t) which is determined by the height of the hindering barrier through which the methyl group tunnels. These are free tunnelling wavepackets. In contrast to most experimental techniques low field, dipole-dipole driven NMR enables the methyl groups to be accelerated and the rotation frequencies of the wavepackets to be changed. This is driven tunnelling. The flexibility of the experiment enables the wavepackets dynamics to be manipulated in a number of different ways. Spectra with broad, asymmetric peaks for both single and coupled methyl groups are presented as evidence of driven tunnelling.