Frequency domain Fourier transform THz-EPR on single molecule magnets using coherent synchrotron radiation

Frequency domain Fourier transform THz electron paramagnetic resonance (FD-FT THz-EPR) based on coherent synchrotron radiation (CSR) is presented as a novel tool to ascertain very large zero field splittings in transition metal ion complexes. A description of the FD-FT THz-EPR at the BESSY II storage ring providing CSR in a frequency range from 5 cm^-1 up to 40 cm ^-1 at external magnetic fields from -10 T to +10 T is given together with first measurements on the single molecule magnet Mn₁₂Ac where we studied ΔM_S = ±1 spin transition energies as a function of the external magnetic field and temperature.