Dear ISMAR members,
It is with great sadness that I convey the news of Shimon Vega's
passing on November 14 at age 78. Shimon was a widely respected leader in
the field of magnetic resonance, known especially for his many conceptual
contributions to modern solid state NMR methods and for the clarity of his
thoughts and presentations. Shimon was a Fellow of ISMAR and the recipient
of the 2015 ISMAR Prize.
Rob Tycko, President of ISMAR
The following obituary was prepared by his colleagues
Daniella Goldfarb and Lucio Frydman:
Shimon Vega was born in Amsterdam on November 14, 1943 and passed away two
days after his 78th birthday. As he would later say: “This was not a
good time and place for a Jewish child to be born, and led to what perhaps
was the most ‘interesting’ part of my life”. At the age of 6 weeks
he was sent to a hideout with a Dutch family until the end of the war, thus
surviving the Holocaust. He grew up in Ouderkerk aan de Amstel, a small
village south of Amsterdam. After obtaining both his B.Sc. and M.Sc. in
Physics in Holland he moved to Israel with his wife Margrit, and completed
his Ph.D. with Prof. Zeev Luz at the Weizmann Institute on Nuclear
Quadrupole Resonance. Shimon stood out already during his PhD, where he
published his thesis papers as a sole author with the full encouragement of
his advisor. This work was the beginning of a joint tackling of the
theoretical and experimental chemical physics underlying magnetic
resonance. After PhD graduation Shimon became Alex Pines’ first postdoc
at Berkeley, where they made pioneering discoveries in the new field of
multiple-quantum NMR. This work would eventually lead to setting the basis
for the fictitious-spin-½ formalism, nowadays a primary tool for
understanding NMR in solids and liquids and gaining recognition in EPR and
quantum optics.
Upon completing his postdoc Shimon returned as a tenure-track faculty to
the Weizmann Institute, where he expanded these studies to half-integer
quadrupolar nuclei. This work, along with the multi-quantum concept, served
as basis for additional future developments in the field that resulted in a
wide variety of materials-oriented research. Shimon continued to focus
mostly on solids NMR and developed new decoupling and recoupling methods,
as well as new kinds of pulses and new structural determination schemes
–most often while relying on magic angle spinning (MAS). In those
late-1970/early-1980 days, MAS was largely viewed from a continuous-wave
perspective; i.e., as an averaging process leading to the cancelation of
second-rank anisotropies and hence sharp spin-1/2 lines. Drawing from the
time-domain perspective that had led to multiple-quantum NMR, Shimon
departed from this outlook, and was among the first to recognize the
complex time-dependencies that underlie MAS as an averaging process.
Starting at Weizmann and furthering these ideas during sabbaticals at MIT
with R.G. Griffin and at Washington University with J. Schaefer in the
1980s, Shimon thus developed sophisticated theories –many of them based
on the Floquet formalism– to advance the understanding of MAS NMR. These
efforts allowed exact computation of MAS spectra under a variety of
scenarios, while leading to a deeper understanding and to new pulse
sequences. They also lead to new methods to evaluate dynamic processes in
MAS NMR, and to the design and interpretation of a variety of discrete
multipulse recoupling experiments. The latter included homo- and
hetero-nuclear dipolar decoupling/recoupling schemes like SEDRA, TEDOR,
RFDR and REAPDOR, that have since become common tools in the biomolecular
and materials NMR arsenal. They also included sensitivity enhancement
schemes, such as the FAM sequence for semi integer quadrupolar nuclei.
During a subsequent stage of Shimon’s solids NMR research he
extended Floquet’s sophisticated formalism to a multimodal format,
capable of accounting for the coherent evolution of a density matrix
subject to multiple, non-commensurate time-dependent processes
simultaneously. Numerous experiments he designed were on the basis of
multi-modal Floquet theories, in particular the high resolution single- and
multidimensional proton NMR phase-modulated Lee-Goldburg sequences (PMLGn).
During the last decade Shimon embarked on yet another venture:
understanding the mechanism of dynamic nuclear polarization (DNP) at high
magnetic fields. He realized the limitation of traditional steady-state
descriptions of DNP, and developed instead quantum mechanical models which
could reproduce and predict important experimental features – helping to
bring about DNP MAS NMR’s renaissance. Shimon continued to be highly
active and productive years after his “formal” retirement, and kept
working on and thinking about magnetic resonance till the day he was
hospitalized.
Shimon was truly exceptional as an educator and scholar, that molded and
enriched the lives of those he met and interacted with. He was an engaging
lecturer that would capture audiences, despite –and perhaps because of–
his relentless refusal to escape from equations and meaningful concepts. He
was a sought-after teacher that in addition to regular courses at the
Weizmann Institute devoted ample time lecturing at high schools, guiding
local kids in visits through the Weizmann labs, and sharing his science
with his community –much before outreach activities became
“fashionable”. Shimon was a remarkable mentor, who trained graduate
students and postdoctoral fellows that are now leaders in the forefront of
magnetic resonance worldwide. But more than anything else, Shimon was an
exceptionally caring human being, who inspired with his generosity in
sharing his knowledge and wisdom, his patience, his unusual capability to
listen, and his modesty. At the Israel Chemical Society 2018 meeting, which
endowed Shimon with its highest Gold Medal award, Shimon summed up some of
these traits in a way that reflected his personality: “I wish to share
with you, my love. Above all my love for my wife Margriet, who in addition
to all the rest, made it possible for me to dedicate much of my time to
science. And for our children who knew what it meant to have a dad in the
lab or abroad or in miluim (army reserve). Let me tell you about my other
love… Magnetic Resonance… I wish to thank the ICS Prize Committee. I
assume that if I had been a member of that committee, I would not have
voted in favor of myself. Why? Because I know what I know and I also know
what I don’t know, but they don’t realize how much I don’t know. It
is a great honor for me to join the incredible list of ICS Gold
Medalists.”
We will miss Shimon greatly, but consider ourselves fortunate to have had
him as fellow traveler during the course of our journey through science and
life.
Daniella Goldfarb and Lucio Frydman
Rehovot, November 2021