Electron Magnetic Resonance (EMR) Overview
Overview
The Electron Magnetic Resonance (EMR) facilities offer users several home-built, high-field and high-frequency instruments providing continuous frequency coverage from 9 to 900 gigahertz (GHz), with additional frequencies available up to 2.5 THz using a molecular gas laser. Several transmission probes are available for continuous-wave (c.w.) measurements that are compatible with a range of magnets at the lab, including the highest field 45 T hybrid. Some of the probes can be configured with resonant cavities, providing enhanced sensitivity as well as options for in-situ rotation of samples in the magnetic field. Quasi-optical (QO) reflection spectrometers are also available in combination with dedicated high-resolution 12/17 T superconducting magnet systems; a simple QO spectrometer has also been developed for use in the resistive magnets (up to 45 T).
2D electron spin echo detected EPR in TEMPOL recorded at 239 GHz and 15K.
In addition to c.w. capabilities, the EMR group boasts the highest frequency pulsed EPR spectrometer in the world, operating at 120, 240 and 336 GHz with 100 ns time resolution. A commercial Bruker Elexsys 680 operating at 95 GHz is available upon request. In the general science building, two superconducting magnets currently serve three spectrometers, as presented in our instruments page. We also continue to develop new instruments. EMR staff members also assist users in the DC facility using broadband tunable homodyne and heterodyne spectrometers. This combination of instruments may be used for a large range of applications in physics, materials science, chemistry and biology, including: studies of optical conductivity and electron cyclotron resonance; electron paramagnetic resonance studies of impurity states, molecular clusters, antiferromagnetic, ferromagnetic and thin film compounds, optically excited paramagnetic states, electron spin-based quantum information devices; and for structural and dynamical studies of metallo-proteins, spin-labeled proteins and other complex bio-molecules.
Why High Fields?
Most EPR research is done at the X-Band frequency of ~9.5 (GHz). K-Band (25 GHz), Q-Band (35 GHz) and W-Band (95 GHz) instruments are also commercially available. EPR at high frequencies of hundreds of GHz and at high magnetic fields of several teslas and more offers numerous advantages:
EMR users
The EMR users represent one of the most interdisciplinary groups at the Mag Lab. The facility typically produces 40 to 45 peer-reviewed journal articles each year, with many in high-impact journals such as Nature and Physical Review Letters. Roughly half of the group's publications appear in American Physical Society journals, with the remainder appearing in chemistry and biology journals. The EMR group is able to provide some financial support for visits to the Mag Lab by first-time users.
For more information contact EMR program director Stephen Hill.
