THz spectroscopy & THz EPR
The THz beamline exploits intense coherent synchrotron radiation (CSR) as emitted from special storage ring modes, for the study of magneto optical phenomena in the energy range from 3 to 150 1/cm. A dedicated THz electron paramagnetic resonance (THz-EPR) facility combines a broad range of excitation and detection schemes with extreme sample environments (in particular high magnetic fields and low temperatures).
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
THz spectroscopy and EPR - Scientific Applications
Methods
IR Spectroscopy, THz spectroscopy, Time-resolved absorption, Polarimetry, Reflectometry
Remote access
depends on experiment - please discuss with Instrument Scientist
BESSY II THz-EPR Setup
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].