Group ESR Spectroscopy

My group uses Electron Paramagnetic Resonance (EPR) also known as Electron Spin Resonance (ESR) Spectroscopy to investigate the structure of novel materials and proteins. Our work is unashamedly collaborative and brings together biologists, chemists, materials scientists and physicists.

Gruppenbild der Physikalischen Chemie vor dem Gebäude, 12 Personen — © Martina Schilling

What is EPR spectroscopy?
EPR spectroscopy is a powerful technique, giving insights into the structure of materials/molecules and proteins. Paramagnetic substances like e.g., unpaired electron spins of radicals, are exposed to a magnetic field to tune the zeeman splitting between the two possible spin states. Subsequently, the resulting energy transitions get probed by microwave (MW) irradiation. Generally, a distinction between two modes of operation is made: Continuous wave (CW) and pulsed MW irradiation.
Both methods incooperate distinct spectral features which can give answers to different structural investigation issues. Our work is widely collaborative and brings together biologists, chemists, materials scientists and physicists.

Available EPR spectrometer:

Bruker Elexsys E580 SuperQ Q-band EPR pulse spectrometer equipped with a closed-cycle He cryostat (3 - 300 K) (resonators: EN 5107D2 Q-Band ENDOR, EN 5107T2)

Bruker Elexsys E580 X-band EPR pulse spectrometer equipped with a closed-cycle He cryostat (3 - 300 K) (resonators: ER4118MD4 ENDOR, ER4118MD5)

Bruker X-band EMXplus CW spectrometer (resonators: SHQE, ER4123D)

Bruker Magnettech ESR5000

Structural Biology

Combining X-ray crystallography, molecular dynamics and nitroxide spin-labeling EPR spectroscopy to obtain and verify structures of proteins in solution (Ilangovan et al, Cell 2017, Bagneris et al Nature Communications 2013, Webster et al Nucleic Acids Research 2012, Phan et al Nature, 2011, Grohmann et al Journal of the American Chemical Society 2010).

Room Temperature MASERs

The MASER (Microwave Amplification by Stimulated Emission of Radiation) is the forerunner of the Laser, but is less well know and developed due to technical challenges. Recently, together with colleagues at Imperial College London, we have been developing a MASER based on the lowest excited triplet state of pentacene in p-terphenyl (Salvadori et al, Scientific Reports 2017, Breeze et al, Quantum Information 2017) and NV- centres in diamond that works at room temperature (Breeze et al, Nature 2018).

Research works

Current theses in the working group of ESR spectroscopy:

Halbach Magnet for Masers

High Performance resonators for Room Temperature Masers

Pulse Shaping for EPR

EPR studies on a Ni3 complex

Spin-Traps

Low Temperature Characterization of a Maser

If you are interested in a thesis, please contact the listed supervisor or just drop by. If there is no thesis listed, but you are interested in EPR spectroscopy, we can discuss individual theses.

Completed scientific papers (bachelor and master theses) and doctoral theses are listed below.

Bachelor-thesis:

Crafting and Analyzing the Finland Radical: A Chemical Adventure
(Maximilian Frisch, Februar 2025)
Photoexcited Triplet States of Dyes in Ionic Liquids and traditional Solvents: A transient and pulsed EPR Study
(Eva Steuer, Oktober 2024)
Synthesis and spectroscopic Characterization of isotopically labeled, aryl - substituted Dithiadiazolyl (DTDA) Radicals
(Ruwen Schank, September 2024)
Synthesis and Characterization of Dithiadiazolyl Radicals
(Tiziano Caldara, September 2023)
Investigation on the photo-excited triplet state of Porphycene by ESR- and ENDOR-spectroscopy
(Maxim Neuberger, August 2022)
Eigenschaften von phosphonium-basierten ionischen Flüssigkeiten mit symmetrischen Ionen
(Daniel Schroeder, August 2022)
Untersuchung der Triplettzuständen sternförmiger Tetrathiofulvalen-Oligofluoren Systeme mittels TREPR-Spektroskopie und DFT-Rechnungen
(Lukas Schank, September 2021)
Die Untersuchung organischer Perylenfarbstoffe in Polysiloxanen-Matrices mittels TREPR-Spektroskopie
(Lukas Schneider, April 2021)
Developments of methods to automate Masing threshold determination
(Yan Fett, April 2021)
Analyse potentiell geeigneter Moleküle für singlet-fission mittels EPR-Spektroskopie
(David Schaaf, März 2021)
Optimierung der stimulierten Emission bei den Stickstoff-Leerstellen eines Diamanten
(Haakon Wiedemann, September 2018)

Master-thesis:

Molecular Encounters: Unraveling Photoexcited Triplet and Radical Dynamics using EPR Spectroscopy
(Maxim Neuberger, Februar 2025)
Verbrückte DTDA-Radikale Synthese und Charakterisierung
(Jonas Bach, Januar 2025)
Hyperfine analysis of Cu zeolites for use in catalysis in diesel engines
(David Schaaf, April 2023)
Optimierung der FT-ICR-MS Detektion und Charakterisierung einzelsträngiger DNA-Oligonucleotiden-Modellkomponenten mit Direktinjektion und gekoppelter HPLC mit jeweiliger Tandem-Massenspektrometrie
(Philip Jochum, August 2022)
EPR- und ENDOR-Spektroskopie an angeregten Triplettzuständen
(Elias Gießelmann, Dezember 2021)
Nitrogen transfer reactions with (Bis)iminophosphoranes and Palladium Nitrenes
(Djana Momper, Dezember 2021)
Wege zum Hochleistungs-EPR-Resonator
(Haakon Wiedemann, Juli 2021)
Photo-excited singlet and triplet states of Reichhardts dye in glass-forming ionic liquids
(Ramona Jost, März 2021)
Spin-polarisation in a stable radical covalently linked to a dye molecule
(Johannes Krämer, Oktober 2020)

From Spins to Solutions - Expanding the Horizons of Electron Spin Resonance (ESR) Spectroscopy
(H. T. A. Wiedemann, April 2025)
Electronic structure and morphology of organic semiconductors and the impact of molecular modifications
(C. Matt, 2021)
https://publikationen.sulb.uni-saarland.de/handle/20.500.11880/31812

PCB Seminar Announcement - SoSe25

We are starting a new seminar series, covering the areas Physics, Chemistry and Biology (PCB). Our guest speakers coming will report on their current research topics, introducing them from a basic level to allow accessibility for an non-expert audience.

Our first seminar will already take place next week Tuesday (13.05.) at 16:00 in our ground floor seminar room (B2 2 - 0.06). Attached is a little flyer with all the dates.

We hope many will be able to attend. Looking forward seeing you.
If you have any questions or comments, please contact Christoph Zollitsch.