Jean Jeener, 1931 – 2023

Jean Jeener at the 1998 International Symposium at the Université Libre de Bruxelles organized for the occasion of his retirement

The Magnetic Resonance community mourns the passing of Prof. Jean Louis Charles Jeener on June 10, 2023 at the age of 91 after a short illness.

Jean introduced two-dimensional NMR spectroscopy and proposed the COSY technique in a lecture at the AMPERE Summer School in Basko Polje, Yugoslavia, September 1971, which was then experimentally demonstrated by Richard R. Ernst. Later, Jean also introduced the NOESY experiment.

His research interest in NMR started with spin thermodynamics and dynamics in solids (“Jeener-Broekaert sequence” for observing dipolar order in solids), progressively extending towards two-dimensional spectroscopy in liquids, superoperators, peak shapes in the presence of molecular rearrangements, the formulation of pulse spectroscopy with full quantization of the field, radiation damping and dipolar field effects in liquids.

Jean was professor of Physics at the Université Libre de Bruxelles from 1960 until he retired in 1996.

Among many distinctions, Jean received the ISMAR Prize in 2001, the Prix Quinquennal of the Fonds National de la Recherche Scientifique, the Ampère Prize, the Russell Varian Prize, the Otto Stern Prize, and was an ISMAR fellow.

Our thoughts are with his family and friends.

The following tribute was written by Guy Lippens, Paul Broekaert, and Alain Vlassenbroek

Jean Jeener was born in 1931. He obtained Chemistry and Physics degrees from the Université Libre de Bruxelles (ULB) in 1953 and 1954. He earned a PhD with Prof I. Prigogine, later Chemistry Nobel Prize winner for his contributions to non-equilibrium thermodynamics, which was followed by a postdoctoral stay with Prof. N. Bloembergen, one of the founders of NMR and later Physics Nobel Prize winner for laser spectroscopy. This academic background explains his initial project upon his return as a professor at the ULB in 1960 to study spin thermodynamics. Transforming the Zeeman order into spin-spin order through a two-pulse sequence (the Jeener-Broekaert echo) was a major contribution from the Brussels group but already carried the idea of increasing the number of pulses to probe new physics. When Jean came up with the idea of a double Fourier Transform and thereby introduced the principle of 2D NMR, experimental difficulties with the home-built apparatus prevented them from realizing the experiment, but not of distributing the idea in the community. It was taken up in the Basko Polje Summer School by Dr. Thomas Baumann, then a graduate student student of Prof. Richard Ernst, who immediately realized its importance and actually managed to implement the idea. A reprint of the historical 1971 lecture notes is available here (Jeener and Alewaeters, Prog.  NMR Spec. 94–95, 75–80,, 2016). Richard Ernst's note to Jean and Dr. Paul Broekaert upon receiving the Chemistry Nobel Prize in 1991 is unambiguous about the intellectual contribution of the Brussels group.

Note to Jean Jeener by Richard Ernst when he was awarded the Nobel Prize in Chemistry

What follows are some very personal recollections by one of us (GL). After a physics undergraduate from Ghent University and Cornell University, I was formally a PhD student in Ghent, but actually doing research in the Biochemistry department at ULB, using solution NMR spectroscopy to obtain the conformation of the oxytocin hormone. People had pointed out to me that Prof. Jeener was an authority in NMR, so I went to see him quite naively with an NMR-related question. When I told him my background, he immediately became enthusiastic, and questioned me about my knowledge of raising and lowering operators to describe the electromagnetic field. “We treat the spin as a quantum object, so doesn’t it surprise you that we treat the pulse as a classical object?” was his question. Three hours of blackboard development later, I left his office without an answer to my (trivial!) question but convinced that I could learn a lot from this professor. As a side note, it took ten more years before he published together with Prof. F. Henin (his wife) the presentation of pulsed nuclear magnetic resonance with full quantization of the radio frequency magnetic field. And when taking him out for dinner together with Erwin Hahn and his wife at the 2004 EUROMAR meeting in Lille, they started scribbling on all napkins to extend the quantum description to the actual coil as well …

As I performed a lot of molecular dynamics simulations during my PhD and wanted to simulate NMR variables such as proton T1 and T2 relaxation times, I took great profit from Jean's earlier work on gypsum demonstrating that one could treat a system of water molecules as an assembly of independent protons, neglecting spin correlations of the two proton spins on the same water molecule. Without any official appointment as a PhD advisor, he took all the time to go with me through these complex spin operator equations and encouraged me to (re)do the full Redfield relaxation theory in the super-operator formalism.

Upon moving to the Pasteur Institute of Lille after my PhD and getting access to a newly installed 600 MHz instrument with a cryogenic probe, our interactions actually became more frequent. We became his experimental laboratory to probe collective effects in NMR ranging from radiation damping to long-range dipolar field effects. In one of these projects, we needed a tiny capillary in a rotor. Jean asked for a Bunsen burner and drew a pipette to the 0.3 mm diameter that they had calculated would reduce the amount of radiation damping. Observing the capillary under a microscope, its diameter proved to be 0.31mm, underscoring that he was first of all a gifted experimentalist. When at the 1994 EENC in Oulu, a heated debate broke out between two eminent members of the NMR community about the quantum or classical description of these collective dipolar field effects, Jean Jeener was there to calm down the debate. This made me fully realize for the first time his authoritative position in the NMR field. He would later publish a paper on the equivalency of both viewpoints.

The last years of his life, Jean Jeener remained interested in NMR but also in the progress of astrophysics and science in general. The interpretation of quantum mechanics was a point where he was intransigent (for an example published only in March 2023, see Jeener, J. L.: More on the demons of thermodynamics, Physics Today, 76, 12–13,, 2023), and he found a similar mindset in Prof. David Mermin. Finally, a couple of weeks before his passing away, he was awarded the Otto Stern Prize, for his lifetime career.

Award of the Otto Stern Prize of the Gesellschaft Deutscher Chemiker to Prof. Jean Jeener on April 15, 2023 by Prof. Jörg Matysik (left) and Prof. Christian Griesinger (right)

With the passing of Jean Jeener, another of the initial heroes of NMR disappears. His legacy, together with that of the other towering figures, will however remain for the generations to come.

Anyone who knew Jean Jeener will know that this great scientist possessed a natural wisdom in many areas, while remaining modest and humble and demonstrating great humanity. Jean will be greatly missed as a caring and inspiring mentor, a dedicated teacher, a friend, and a wonderful person who had the ability to touch people's lives ...