Klaus Möbius, 1936 – 2024

Klaus was a pioneer of modern advanced EPR spectroscopy, including electron-nuclear double resonance (ENDOR), and cw and pulse high field EPR; he applied these techniques to many pertinent questions in chemistry and the life sciences. On the occasion of his 85^th birthday he wrote an autobiography, in which he is telling the story of his life (1).

Klaus Möbius was born 1936 in Berlin and studied physics at the Freie Universität Berlin (FUB), where he also received his doctoral degree (1965). After his habilitation in Experimental Physics 1969 at FUB he spent a postdoctoral year with his family at UC Riverside in California. Back in Berlin he received a position as Professor at the Physics Department of the FUB in 1971. In the following years Klaus Möbius and his group built up a variety of multiple magnetic resonance methods, including local and distant ENDOR and TRIPLE resonance, optically detected magnetic resonance (ODMR) and nuclear quadrupole resonance and applied these methods to organic and organometallic molecules in various matrices in their singlet and doublet ground and excited triplet states.

Within one decade his laboratory became one of the leading places for magnetic resonance, attracting many international guests and collaborators.

A highlight during these years was the application to photosynthetic reaction centers of bacteria, plants, and related model systems.  This seminal work elegantly demonstrated the power of EPR/ENDOR spectroscopy in determining the electronic structure of paramagnetic species in complex biological systems and has substantially contributed to understanding light-induced charge separation in photosynthesis.

Initiated by earlier work of Yakov Lebedev (Moscow) Klaus Möbius also engaged in the development of High Field EPR and published details of a cw HF-EPR instrument at 95 GHz in the mid-eighties, which was later extended to time resolved (transient) and pulse work, including ESEEM/HYSCORE, DEER/PELDOR, ELDOR-detected NMR (EDNMR) and pulse ENDOR – with in-situ light excitation and a large accessible temperature range. This opened many interesting applications across the sciences – especially the life sciences - that are described in his monograph on HF-EPR (2) and a recent review article (3). The field was boosted - in Germany and worldwide - by the Priority Program “High Field EPR in Biology, Chemistry and Physics” of the Deutsche Forschungsgemeinschaft (DFG). The program was co-initiated and coordinated by Klaus Möbius (1998-2004). It was instrumental in the further development and application of higher fields and frequencies in many EPR laboratories, in close analogy to the earlier development of NMR spectroscopy.

Klaus, stayed in Berlin during his entire career. His dedication to his home city, the great scientific surrounding with many cooperation partners, and the excellent funding provided by the DFG and FUB contributed to this decision. This enabled a continuity of his research that could hardly be matched anywhere else. At FUB he engaged in teaching the next generation of scientists. He gave truly excellent lectures in the classroom, and also in many schools dedicated to Magnetic Resonance and on national and international conferences to which he was often invited.

After his formal retirement at the FUB (2001) he successfully continued his work as permanent guest scientist at the Max Planck Institute for Chemical Energy Conversion in Mülheim/Ruhr. It is remarkable that Klaus published over 100 scientific papers and wrote 3 books after his retirement. For his excellent work he received many awards, including the Bruker Prize, the Max Planck Research Award, the International Zavoisky Award, the Philip-Morris Research Award, the AMPERE Prize, and the Gold Medal of the International EPR Society. An overview of his impressive list of awards, fellowships and other honors, his function in academic societies, and a list of his scientific publications can be found in (4).

Klaus Möbius was a strong advocate for the International Society of Magnetic Resonance. He always pointed out the importance of ISMAR for bringing together scientists interested in magnetic resonance from very different disciplines around the world – a unique opportunity to learn about recent developments and applications in various fields of science. Klaus was invited to many ISMAR meetings to lecture about his recent results at the interface of EPR and NMR. In 2009 he was elected as Fellow of ISMAR. He was one of the founding fathers of the European Foundation of EPR Societies (EFEPR) and its first president (1991-1994) and worked also for many years for the International EPR Society.

During his entire career he was establishing and maintaining sustainable international cooperations worldwide, e.g. with Russia, Israel, Japan, Italy and many other nations, which particularly benefited the next generation of young scientists. For these activities he was awarded the Verdienstkreuz 1. Klasse (German “Federal Cross of Merit, First Class”) in 2006.

Klaus Möbius has worked his whole life for international understanding, for peace and actively against war - against the use of weapons, especially nuclear weapons. Also nuclear power plants were taboo for him. The deterioration of international scientific relations in recent years due to the military conflicts in Ukraine and the Middle East was terrible for him.

He was also concerned about the massive use of fossil fuels leading to global warming and engaged in research to develop alternative, sustainable energy sources. His great interest and work in natural and artificial photosynthesis was directly related to this problem. His fascination of photosynthesis is documented by the play "Life on Earth through Photosynthesis", which he wrote together with Giovanni Giacometti (Padua), published in 2016.

His interests and knowledge far beyond the natural sciences is documented in a beautiful way by his last book the “Möbius Strip Topology”, a comprehensive work with excursions into science history, chemistry, nanotechnology, material science, architecture, art and music (5).

Klaus was convinced that good scientific cooperations should be built upon personal relations and friendships. He deeply respected other scientific disciplines, from which he obtained important impulses for his research. His students and postdocs appreciated his interdisciplinary scientific approach, it often laid the foundation for their later work. I personally couldn't have wished for a better scientific teacher, mentor and advisor for my professional career.

With Klaus Möbius we are losing an excellent scientist, a strong advocate for magnetic resonance and for science in general, a great human being and for many of us a good friend.

We will not forget him, preserve his memory and continue his work.

Wolfgang Lubitz                                        Mülheim an der Ruhr, November 2024

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