Nicholas Kurti and Erwin Hahn

In continuing these installments of my scientific reflections, I should say a little more about Nicholas Kurti and Erwin Hahn. Kurti was my scientific "grandfather", one of the brilliant Jewish refugees acquired by the Clarendon Laboratory in the 1930s. He held the record for achieving the lowest laboratory temperature of 1 millionth Kelvin when I first knew him. Nicholas was immensely kind and he and his English wife Gianna regularly hosted graduate students in their home.

I first met Erwin Hahn in 1971 on one of his visits to Nicholas and Gianna Kurti in Oxford. I had the pleasure of meeting him again in Krakow in 1974. I had no idea how great was his science. If any work ever deserved a Nobel Prize, Hahn's discovery of the spin echo certainly did. This is what I wrote of him in my 2011 book, "Translational Dynamics and Magnetic Resonance". "Of all the developments that have assisted NMR measurements of translational dynamics, none is as important as the discovery of the spin echo by Erwin Hahn in 1950. Indeed, it can be argued that the power of the spin echo underpins all of modern NMR. The formation of the echo, with its inherent time-reversal properties, not only causes lost signals to re-appear, it also has the effect of removing some nuclear spin interactions while retaining others. Hahn pointed out that in the case where the magnetic field was inhomogeneous, the signal obtained by method was sensitive to translations of spin-bearing molecules, providing, for example, a means of measuring random Brownian motion."

Erwin was to become a friend, mostly through my association with Alex Pines in Berkeley. He describes his current position as being emeritus "postdoctoral fellow" in Alex's lab!




Part 2: Pamerston North
I stayed in Oxford for another year as a postdoctoral fellow, but I was determined to go back to New Zealand to attempt the task of doing international science from my home base. My forebears, Rutherford included, just had to make the shift to expatriate status in order to do any serious science. But things were changing at home, not the least of which was the advent of cheap long-haul air travel. Suddenly NZ was connected to the world in a different way. And there were some brave pioneers from whom to take inspiration. Kiwi theoretical physicist Dan Walls had, in 1972, returned from Roy Glauber’s group at Harvard to start a school of quantum optics in NZ. Dan later became a Fellow of the Royal Society and winner of the Dirac medal and prize. Cancer claimed him too, in 1999. I returned home in late 1974 to a lectureship in Physics at Massey University, an upstart institution with an agricultural college background, and a small but feisty science faculty led by a larger-than-life biochemist, Dick Batt. Dick came from my hometown of Wanganui. Maybe that’s how I got the job. But I was grateful for the employment, and joined a small group of physics colleagues inside a larger Chemistry Department. There was no physics research equipment at all, but the chemists had just acquired a JEOL FX60 NMR spectrometer. It was just a remarkable machine, with a lovely light pen interface, the first for JEOL of the new generation of pulsed Fourier transform instruments.

The physical chemist in charge of the FX60 was a Lancastrian immigrant, Ken Jolley. I couldn’t have had a better teacher or more generous colleague. He allowed me to share in this wonder and to start a research program using the spectrometer. And being in that chemistry environment could not have been better for me as I made my transition from a rather narrow-focused physicist to one who saw the wonders of chemistry, of the world of molecules, with all the opportunities for physics that this field of research presented. With Metka Luzar’s talk in my mind, I set about building a pulsed field gradient system that we could attach to the FX60. In that I was assisted by an able graduate student named Craig Trotter. We built the electronics and gradient coil and quickly discovered that there were some technical problems plaguing this method that were ripe for tackling. These included gradient pulse area mismatch, sample vibration, and eddy current effects. By good luck we made some progress, and that led to a fruitful period in which my collaborators and I measured polymer diffusion, as well as small molecule diffusion in anisotropic and heterogeneous environments.

It wasn’t long before NMR micro imaging became a focus of our work. The apparatus building was result of a most remarkable graduate student named Craig Eccles. Craig was not only a fine physicist but also an electronics and software genius. In the mid-1980s, with Craig, and new Chinese student Yang Xia, we were using our NMR microscope to image flow in wheat grains in vivo, impossibly difficult but very effective. This work helped start a new field of research in which sub-100 micron structure was revealed in soft materials and biological tissue from the perspective of the interpenetrating liquid molecules. NMR Microscopy was the subject of my first book, published by OUP in 1991.

Photos in order: Nicholas Kurti, Alex and Erwin, Erwin and me, Ken Jolley and me.