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Paul T. Callaghan

Massey University

Publishes on NMR spectroscopy and applications, Advanced MRI Techniques and Applications, Advanced NMR Techniques and Applications. 262 papers and 14.4k citations.

262Publications
14.4kTotal Citations

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Top publicationsby citations

Principles of Nuclear Magnetic Resonance Microscopy
Paul T. Callaghan|Unknown|1991
Cited by 3.6k

Abstract Nuclear magnetic resonance imaging is best known for its spectacular use in medical tomography. However, the method has potential applications in biology, materials science, and chemical physics, some of which have begun to be realized as laboratory NMR spectrometers have been adapted to enable small scale imaging. NMR microscopy has available a rich variety of contrast including molecular specificity and sensitivity to molecular dynamics. In NMR imaging the signal is acquired in k-space, a dimension which bears a Fourier relationship with the positions of nuclear spins. A dynamic analogue of k-space imaging is the Pulsed Gradient Spin Echo (PGSE) experiment in which the signal is acquired in q-space, conjugate to the distances moved by the spins over a well-defined time interval. q-space microsocpy provides images of the nuclear self-correlation function with a resolution some two orders of magnitude better than is possible in imaging the nuclear density. As well as revealing the spectrum of molecular motion, PGSE NMR can be used to study morphology in porous systems through the influence of motional boundaries. This book explores principles and common themes underlying these two variants of NMR Microscopy, providing many examples of their use. The methods discussed here are of importance in fundamental biological and physical research, as well as having applications in a wide variety of industries, including those concerned with petrochemicals, polymers, biotechnology, food processing, and natural product processing.

NMR microscopy of dynamic displacements: k-space and q-space imaging
Paul T. Callaghan, C.D. Eccles, Yong Xia|Journal of Physics E Scientific Instruments|1988
Cited by 303

The superposition of pulsed gradient spin-echo (PGSE) and NMR imaging experiments results in a spin density image which is phase and amplitude modulated according to the local self-correlation function for nuclear spin displacements over the time between the PGSE gradient pulses. It is shown that such an experiment can image both static and dynamic spin displacements, the reciprocal space for these image spaces being termed k-space and q-space respectively. Simultaneous imaging of diffusion and flow at microscopic resolution is demonstrated and the Poiseuille velocity distribution agrees well with the velocity map obtained for the motion of water in a 0.7 mm capillary tube.