By using un-recommended experimental operations on an expensive instrument, I happened to rediscover what was called spin-locked echo. As a result, I became the first in applying long microwave pulses to observe "locked" electron spins decoupled from their neighbor nuclei.
In 1993, Prof Pilbrow obtained in conjunction with several researchers a relatively large ARC grant to purchase pulsed electron spin resonance spectrometer. I was hired as a Research Fellow to run it.
Instead of simply following the menu provided by the maker, I privately tried unconventional operations in order to see new phenomena. During such trial-and-error, by the way, I had burnt at least two expensive detectors.
One day after everyone had left for home, I tried to increase the length of the microwave pulse while monitoring the seemly well-known Hahn echo. To my surprise, the electron spin echo could always be observed so long as the length of the pulse was smaller than the spin-lattice relaxation time. More interestingly unexpected, the time position of the echo is merely determined by the time separation between the two pulses, irrespective of their pulse lengths! See Fig. 1(B).
To ensure this was new phenomenon, I thoroughly scanned the published literature. Before long, I learnt that this type of spin echo was mentioned by Hartmann and Hahn in 1962 in their pulsed nuclear magnetic double resonance studies, but no one had ever reported a locked echo from electron spins. Could I be the first to observe locked electron spin echo?
By carefully reading the paper by Hartmann and Hahn, I gradually realized that the spin-locked echo can be described in term of spin-lattice relaxation in rotating frame coined by Redfield so long as one should not be confined to short-pulse experiments.
Today, it still seems intrigued for me to run into this observation, as if I deserved for this reward. In my Ph.D. thesis, I had quantitatively explained an unexplained effect called saturation-transfer electron spin resonance, so I had to read a lot. Besides, I also explained some continuous-wave (CW) NMR results observed by Redfield in 1955 using my new theory.
Interestingly enough, it was based on his CW NRM results, Redfield introduced a new concept in magnetic resonance: namely "spin-lattice relaxation in rotating frame," which idea was later visualized as spin-locking as if these spins being experienced resonantly excited were disconnected from the rest of spins in the sample and hence were locked behind bars.
So, it's time to publish the observed the locked electron spin (LES) as all of the pulsed electron spin resonance studies had been confined to short pulses compared with relaxation times. Our paper was received by the editor of Chemical Physics Letters on August 26, 1993, but it was delayed for nearly 8 months before its publication. An unknown referee repeatedly asked us to revise our draft. Finally, annoyed by the unprofessional behaviors, Prof Buckingham, the editor of the journal, stepped in, telling us that he would publish our paper irrespective of the referee's further comments.
Today, locking either electron or nuclear spins has become a routine in studying spin dynamic in relation to develop quantum computing. I am proud of being the first to observe the echo of locked electron spins.
My advice to young students is this. If you wish to make some truly creative contribution, you should not take popular ideas for granted.
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