Search Contact
University of Cambridge Home Chemistry Department Home Professor Ray Freeman
University of Cambridge >  Department of Chemistry >  Academic Staff >  Ray Freeman

Professor Ray Freeman

Jesus College

Telephone: 01223 336450

Professor Ray Freeman is now formally retired but continues work on high-resolution NMR spectroscopy in his "spare time". He has just written a textbook entitled "Magnetic Resonance in Chemistry and Medicine" (Oxford University Press). This draws together the two main applications of magnetic resonance in simple, non-mathematical language suitable for students, chemistry graduates, medical doctors, healthcare professionals, and even actual patients about to undergo an MRI scan. His previous books were "A Handbook of Nuclear Magnetic Resonance" Second edition, Pearson, 1997, and "Spin Choreography" Oxford University Press, 1997.

His latest research projects (with Dr Eriks Kupce) are aimed at speeding up multidimensional NMR spectra, a goal of particular importance to protein chemists who sometimes spend days acquiring data for a single investigation. One approach uses prior information from one-dimensional spectra to set up an array of selective radiofrequency pulses tuned to irradiate the key chemical sites. By using a Hadamard encoding scheme this multiple-irradiation method achieves the same multiplex advantage as conventional Fourier transform NMR. For biomolecules uniformly enriched in carbon-13 or nitrogen-15, this freedom to focus on particular sites not only speeds the measurement but also offers the equivalent of specific isotopic enrichment. Figure (B) illustrates the simplification of the three-dimensional HNCO spectrum of agitoxin (a 4 kDa protein) with a speed advantage of 200 compared with the conventional method (A).

multidimensional NMR spectra

The second approach restricts data acquisition to a small number of plane projections of the multidimensional spectrum recorded at different inclinations. These projections are then used to reconstruct the full spectrum by means of deterministic or statistical algorithms similar to those employed in X-ray tomography to derive a three-dimensional image of a patient. Both the Hadamard method and projection-reconstruction can increase the speed of measurement by orders of magnitude, opening the door to even higher-dimensional spectra and investigations of time-dependent phenomena.

Kupce, Nishida and Freeman, Progress in NMR Spectroscopy, vol. 42, pp 95-122 (2003).

Kupce and Freeman, J. Am. Chem. Soc. vol.126, pp 6429-6440 (2004).

Freeman and Kupce, Current Analytical Chemistry, vol. 2. pp 101-105 (2006).