THz spectroscopy & THz EPR
THz Spectroscopy & THz Electron Paramagetic Resonance (EPR)
Electron paramagnetic resonance (EPR) provides unique information on the magnetic structure-function relationship of materials containing unpaired electron spins. Combining this method with coherent synchrotron radiation, THz-EPR detects EPR excitations over a very broad energy and magnetic field range in a single spectrometer.
Selected Applications:- determine spin state energies and interaction parameters of electron spins in the THz/FIR range for transition metal ion and lanthanide complexes and materials (e.g. molecular magnets, spin-crossover materials, catalysts)
- investigate spin-phonon couplings
- study (magnetic) phase transitions
Methods
IR Spectroscopy, Time-resolved absorption, Polarimetry, Reflectometry
Remote access
depends on experiment - please discuss with Instrument Scientist
| Beamline data | |
|---|---|
| Energy range | 2 cm-1 - 10000 cm-1 |
| Energy resolution | 0.0063 cm-1 |
| Flux | 5 mW / mm2 |
| Polarisation | variable |
| Focus size (hor. x vert.) | > 0.3 x 0.3 mm |
| Phone | +4930 8062 13170 |
| More details | THz-Beamline |
| Station data | |
| Temperature range | 1.8 - 400 K |
| Pressure range | For details contact the Instrument Scientist. |
| Detector | 1.6 K (pumped) and 4.2K Si-Bolometer, InSb-HEB, DTGS, Ultrafast Schottky Diode (ACST) |
| Manipulators | Sample VTI in 12 T magnet |
| Sample holder compatibility | For details contact the Instrument Scientist. |
| Additional equipment | Magnetic field: ± 12 Tesla |
| Pump laser (3.5 - 1600 mW) | 405 / 450 / 520 / 532 nm |
Motivation
Main science drivers are investigations in spin coupling energies of high-spin transition metal and rare earth ions. Spin coupling energies are sensitive probes of the electronic structure and determine magnetic properties of compounds with unpaired electron spins. The latter are highly desired pieces of information, as high-spin paramagnetic ions determine the function of many vital catalytic processes in proteins and synthetic complexes, as well as the properties of systems with large exchange couplings, e.g. single-molecule magnets (SMMs), energy materials or strongly correlated solids.
Frequency-Domain Fourier-Transform THz-EPR (FD-FT THz-EPR)
EPR is capable of providing unique information on magnetic structure-function relationships of materials containing unpaired electron spins. However, conventional single frequency EPR frequently fails in cases where spin transition energies exceed the quantum energy of the spectrometer (typically <4 cm-1). Employing very short electron bunches (low-α), we have demonstrated that coherent synchrotron radiation (CSR) [1, 2]-based FD-FT THz-EPR [3] provides a unique tool to overcome this restriction. Our approach allows for EPR excitations over a broad energy (3 cm-1 – 700 cm-1) and magnetic field range (-12 T – +12 T) in a single spectrometer. FD-FT THz-EPR has been successfully applied to high-spin ions in SMMs [4], single-chain magnets (SCMs) [5], catalytically relevant integer and non-integer high-spin transition metal ion complexes [6, 7], as well as in proteins [8] and strongly correlated solid-state systems [9].
Remote access
Remote access & control available for mail-in samples, possibly also staff-assisted experiments upon request.
References
[1] M. Abo-Bakr, et al. Phys. Rev. Lett., 2003, 90, 094801.
[2] K. Holldack, et al. Phys. Rev. Lett., 2006, 96, 054801.
[3] J. Nehrkorn, et al. J. Magn. Reson., 2017, 280, 43739.
[4] D. Pinkowicz, et al. J. Am. Chem. Soc., 2015, 137, 14406.
[5] M. Rams, et al. Chem. Eur. J., 2020, 26, 2837.
[6] J. Nehrkorn, et al. Inorg. Chem., 2019, 58, 14228.
[7] J. Krzystek, et al. Inorg. Chem., 2020, 59, 1075.