Alex Pines 1945-2024

Shortly after Alex’s birth, the family relocated to Bulawayo in present-day Zimbabwe. Bulawayo provided a safe and nurturing environment for the young Pines family, offering Alex a childhood filled with cherished memories and formative experiences. It was also the source of his distinctive English accent, which often puzzled those he met.

At the age of 16, Alex made a bold decision to leave the refuge that Bulawayo had given the Pines’ family (and to many others who were trying to recover from WW2) and moved alone to Israel–with his family following thereafter. There, he enrolled in an agricultural boarding school, where students offset tuition costs by working in the fields and tending livestock. This experience taught Alex resilience, discipline, and a deep appreciation for hard work. It was also during this time that he encountered a young science teacher named Ze’ev Luz, who would later become a world-renowned spectroscopist at the Weizmann Institute. Both Alex and Ze’ev would recount with fondness mutual experiences from those severely rationed, highly-disciplined days.After completing high school, Alex pursued dual degrees in mathematics and chemistry at the Hebrew University of Jerusalem. Initially drawn to mathematics by his father’s influence, Alex’s interest in chemistry grew during his undergraduate years. As could have been expected from a brilliant undergraduate, it was not long before Alex was working hands-on in research, joining the group of Prof. M. Rabinovitch for a string of widely cited dynamic NMR studies. A pivotal moment in Alex’s academic journey came when he read Linus Pauling’s seminal book “The Nature of the Chemical Bond.” The book’s mathematical elegance and profound insights into chemical structure and bonding inspired Alex to pursue a Ph.D. in chemistry (1). Determined to expand his horizons, he set his sights on the United States. Alex’s ever-enlarging horizons demanded that this Ph.D. be pursued in the US, and toward this end Alex submitted applications to all major universities and was accepted in all but UC-Berkeley (2).  An undeterred Pines decided to go to MIT, joining one of the foremost experts in the NMR world at that time: Prof. J. Waugh.  Waugh, together with coworkers that would eventually become themselves luminaries in the field (Griffin, Rhim, Haeberlen), was then revolutionizing NMR with the realization that numerous phenomena that had hitherto been described based on statistical spin thermodynamics, were manifestations of a many-body coherent quantum dynamics that could be liable to microscopic control and manipulations. This in turn led Alex to develop experiments that were both fascinatingly deep and useful, including reversals in the dynamics of multiple interacting spins (PRL, 1970). These “resuscitations” of signals that had decayed to zero appeared to fly in the face of basic thermodynamic principles, but in fact paved the way for further multi-spin manipulations –culminating in the classical Proton Enhanced Nuclear Induction Spectroscopy approach for porting the polarization of protons into dilute 13C spins in organic solids (JCP, 1972). The full analysis of the cross-polarization paper that then followed by Pines, Gibby and Waugh (JCP, 1973) helped to lay the foundations of solid-state NMR as we know it and has been cited over four thousand times. Alex performed these experiments with a double-resonance high-power home-built pulsed NMR spectrometer and probe, an instrument that he was particularly proud of. Some of us remember Alex flashing slides taken from his original lab-book with the circuitry he had to design to carry out these multi-pulse experiments; he would also recall how his long days and nights sitting at such console would earn him Waugh’s appreciation, as well as the title of the console’s official “hermitian operator”.

Alex followed his groundbreaking Ph.D. by launching an independent academic career at the University of California Berkeley, starting in 1972 as assistant professor in chemistry. For the next fifty years Pines and his coworkers were a constant source of amazement, coming up with a string of fundamental ideas and experiments straddling the interface between magnetic resonance sciences, and “magical realism”. Oftentimes, upon reading or hearing about Alex’s discoveries, one could not but wonder: “how did he even conceive the possibility of that idea?” 

The quality and quantity of groundbreaking proposals that came out of the Pines Lab are simply too numerous to mention; still, in this MR-oriented summary, one cannot but dwell on at least some all-time classics. Right off the bat Alex –together with S. Vega, D. Wemmer, M. Mehring and others–unveiled the unique opportunities that could arise from multiple-quantum manipulations: first when indirectly detected via then brand-new 2D NMR methods, thereafter when used for spin decoupling, and eventually when used for spin-counting in complex materials.  In the latter instance Alex’s multiple-quantum solid state NMR experiments - involving once again personalities such as W. Warren, D. Weitekamp, J. Baum, M. Munowitz and others - demonstrated two mind-boggling phenomena: the extremely high number of spins that NMR could entangle, and the ability of advanced pulse sequencing to selectively discriminate among hundreds of such entangled states.  It is not a surprise then that when the late Charlie Slichter decided to reprint a new edition of his classic textbook on fundamentals, multiple-quantum NMR earned a chapter of its own.  

Despite their usefulness, there was something in these solid-state NMR experiments that always bothered Pines: the orientation dependence of their effects, that posed so many resolution and analysis problems. Magic-angle-spinning could of course take care of the chemical shift anisotropy –but what about those dipolar and quadrupolar couplings that were so obnoxiously general, and would not go away by MAS? To each, Alex conceived solutions of their own. For dealing with second-order quadrupolar broadenings he realized –together with A. Samoson, J. Virlet, B. Chmelka, K. Mueller, and others– that if anisotropies would not sharpen by spinning samples at any single axis, one should rotate at multiple (or even variable!) axes.  One of us (LF) cannot forget to this day the awe impressed by that 1988 Molecular Physics paper describing double-rotation: MAS was so challenging in those days, that how could one dare to spin a spinner! The influence that these and other methods had in the study of materials in general and in our own careers (LF’s in particular) is well known, but in those days, these proposals were just visionary. Seeing fewer contemporary applications but certainly not less creative was one of the solutions that Alex conceived for getting rid of dipolar couplings: since these anisotropies are imposed by the presence of the NMR magnet, let’s record spectra at zero field: no magnet –no problem!  Naturally, doing NMR without a magnetic field raises some challenges, yet not one to be easily scared Pines –together with A. Thayer, A. Llor, K. Zilm, D. Zax and others– proposed multiple solutions to this problem. Working without magnetic field also raised sensitivity issues, a topic that Pines addressed extensively with yet another battery of discipline-launching proposals. Early examples of these included hyperpolarizing samples by xenon-based optical pumping (D. Raftery, H. Long, C. Bowers and others), and later diamond-based systems (C. Meriles, C. Avalos, A. Ajoy, D. Suter and many others).  Getting rid of the magnetic fields also led Alex into the search for non-inductive alternatives that could enable the acquisition of NMR spectra. These efforts led to seminal SQUID-detected NMR studies (A. Trabesinger, S. Hwang, et al), and optics-based atomic magnetometry studies often involving para-hydrogen-based forms of hyperpolarization (V. Bajaj, M. Ledbetter, T. Theis, J. Blanchard and others).  These efforts were remarkably interdisciplinary, and over the decades led to numerous symbiotic collaborations with other research groups including of J. Reimer, E. Hahn, D. Budker, J. Clarke and others –collaborations whose fruits are still being gathered.

Pines was not only a brilliant scientist but also a passionate educator, dedicating himself to teaching chemistry to thousands of Berkeley undergraduates–with particular attention to the introductory course for non-majors. Pines won every teaching award given by the Berkeley campus, spending hundreds of hours preparing, then delivering, lectures on chemistry that were illustrated with demonstrations, group discussions, and novel assessment schemes that worked for a course with an enrollment of over one thousand per term. His keen insight into the visual display of information led to legendary (and sometimes controversial) talks, such as those employing road signs that poignantly highlighted popular culture as well as group theory. As a mentor, Alex cultivated a global network of students, postdocs, and collaborators affectionately known as the "Pinenuts." This community, characterized by its spirit of innovation and mutual support, continues to advance the frontiers of science while embodying Alex’s values of generosity, humility, and curiosity.

Alex’s contributions to science and education were widely recognized. He was a member of the National Academy of Sciences and the Royal Society, and held honorary degrees from the Universities of Rome, Paris, Marseilles, Nanak Dev Amritsar, and the Weizmann Institute. His numerous awards included the Langmuir Medal and the F.A. Cotton Medal of the American Chemical Society, the Faraday Medal of the Royal Society of Chemistry, Euromar’s Russell Varian Prize, and the Wolf Prize for Chemistry (together with Richard R. Ernst). In his honor, UC Berkeley established the Pines Magnetic Resonance Center, and the Alexander Pines Endowed Lecture in Physical Chemistry.

The paragraphs above are but a very partial description of Alex’s achievements, overlooking his fundamental contributions to spin decoupling; to broadband and selective excitations in NMR and MRI; SPINOE, HyperCEST and other forms of polarization transfer; new ways for improving NMR’s resolution and sensitivity (shim-pulses, magic-angle field spinning); basic topics in quantum control (geometrical phases, gauge choices, with iterative control maps); targeted NMR sensors for molecular imaging and microfluidic (“lab on a chip”) technologies. We also neglected dozens of discoveries that greatly advanced the fields of chemistry and materials. Still, we trust that these paragraphs manage to convey an idea of the magic that Alex brought to his science, not the least of which was the diversity of undergraduate and graduate students, postdocs, sabbatical visitors and collaborators that passed through Alex’s lab. 

Alexander Pines was more than a scientist; he was a force of nature. His brilliance, creativity, and passion transformed the field of magnetic resonance and touched the lives of everyone who had the privilege of knowing him. As we reflect on his extraordinary life, we are reminded of the power of science to inspire, connect, and uplift.

The Pinenuts, along with the broader scientific community, will carry forward Alex’s legacy, striving to emulate his boundless curiosity, generosity, and humanity. In doing so, we honor his memory and ensure that his impact on the world continues to grow.

Jeffrey A. Reimer and Lucio Frydman, December 2024

 1. Alex had a great appreciation for Pauling, with the two largest posters hanging in Alex’s old Hildebrand office being those of Pauling with the orange, and Maradona.

 2.  In his College of Chemistry 2000 commencement address Alex told the story of Berkeley-Chemistry turning him down, assuming a background in Africa and Asia would not qualify his language skills for teaching; he later received the University of California Distinguished Teaching Award and the Robert Foster Cherry Great Teacher Award at Baylor University.