Ray Freeman's career was devoted to the study of nuclear magnetic resonance (NMR). Initially, he focused on the theory and application of double resonance and double-quantum effects, using them to determine relative signs of coupling constants. He devised an inversion recovery method for measuring spin-lattice relaxation times, and the ';INADEQUATE' pulse sequence for enhancing the sensitivity of carbon-13 in natural isotopic abundance.
He was one of the first to investigate the methodology and applications of two-dimensional NMR, a technique now routinely exploited for molecular structure determination. He devised the 'INEPT' coherence transfer experiment for enhancing signals from low-sensitivity nuclei, which became a standard module in many pulse sequences. He also explored the 'BURP' scheme for making radiofrequency pulses band selective. By devising novel cycles of composite or adiabatic radiofrequency pulses, he enhanced the efficiency of broadband decoupling by orders of magnitude.
Ray achieved sparse sampling of multidimensional spectra by a novel projection-reconstruction scheme, significantly reducing experimental durations. He achieved a similar advantage by encoding the excitation according to a Hadamard matrix.
Professor Raymond Freeman FRS died on 1 May 2022.
Emeritus Professor of Magnetic Resonance, Jesus College, University of Cambridge
Interest and expertise
Nuclear magnetic resonance, physical chemistry
For introducing new techniques in high resolution nuclear magnetic resonance spectroscopy, particularly the development of two-dimensional Fourier transform methods.
In recognition of his seminal contributions to the development and understanding of nuclear magnetic resonance (NMR) methods. NMR is today the prime analytical tool for the study of molecular structure and dynamics, with enormous impact in chemistry, mate