High-Frequency/High-Field EPR and ENDOR at 94 GHz

The ELEXSYS family of EPR spectrometers now includes two W-band systems, the E600 and E680. The former is optimized for CW-EPR experiments at 94 GHz, while the E680 operates in both CW- and FT-mode. These high-class research instruments provide a maximum in performance and flexibility while still being easy to operate. Thus all of the advantages of high frequency EPR become readily accessible.

This setup provides an accurate final operating frequency - a must for all g-factor measurements. Flexibility in the system is assured by the modular architecture, allowing the system to be setup as a CW or a combined FT/CW instrument. System operation can be switched from CW to FT or even from W-Band to X-Band at the push of a button. The variable-temperature W-band TeraFlex probehead operates from 4 K to 300 K.
Samples can be exchanged at any temperature. High precision cavity matching, tuning and sample positioning mechanics facilitate high sample throughput with easy handling. For bridge and resonator tuning a 400-MHz wide tuning display is generated and detected on the IF. All these hardware features are complemented by the Xepr software with its easy-to-learn graphical user interface.

Main Features

W-Band bridge
  • Precise microwave power setting over a 60 dB range in W-band
  • All FT-EPR relevant parameters such as pulse power, width and phase are set and monitored on the intermediate frequency (IF) at X-band
  • High spectral purity and sensitivity are achieved by the combination of a fixed frequency oscillator and a PLL circuit

Additional Features

  • The high magent field required for W-band operation requires a superconducting magnet, however not all superconducting magnets are sutiable for EPR. Thus the EPR 6T SC was developed with EPR spectroscopy in mind.
  • As high frequency EPR, in particular pulse EPR, has evolved so have the desires of the EPR spectroscopist. Depending on the pulse EPR experiment, certain advantages are available with more microwave power. For such situations, we offer two W-band bridge upgrades.

Technical Details

•94 GHz operation frequency

•CW and FT operation


•100 mW, 400 mW and 2 W power options

•Single mode resonator

•Sample temperature: 4-300 K

•Superconducting magnet

  • 6 T main coil
  • 0.2 T sweep coil

Advantages of High Frequency EPR

MW-Nutation of Coal Sample at 94 GHz. The nutation period is 62 ns with the 400 mW High Power Upgrade unit.
  • Increase in spectral resolution due to the higher magnetic field.
  • Increase in detection sensitivity for samples of limited quantity due to higher resonator filling factor.
  • Increase in orientation selectivity in the investigation of disordered systems.
  • Accessibility of spin systems with larger zero-field splitting due to the larger microwave quantum energy.
  • Better separation of the ENDOR spectra of different nuclei.
  • Improvement in the ENDOR detectability of low-frequency nuclear spins.
  • Simplification of spectra due to the reduction of second-order effects at high fields.

EPR 6T SC: The W-Band Superconducting Magnet

EPR 6T SC: The W-Band Superconducting Magnet

The second generation of W-band superconducting magnet features a horizontal field, a main coil with 6 T sweep range, permanent leads and a 2 kG high resolution sweep coil. The state-of-the-art magnet design features permanent leads for the main coil and sweep coil with a longer helium hold time compared to similar designs. Both, main and sweep-coil are connected to the newly developed power supply. Easy and safe operation is accomplished by a new software interface which allows switching between the two operation modes just by a mouse click.

W-Band Bridge High Power Upgrades

4-Pulse DEER time traces: 400 mW High Power Upgrade (red, upper) and 100 mW High Power Upgrade (green, lower)

For pulse EPR measurements, where short pulses and large excitation bandwidths are desired (ESEEM, DEER, and FT), three W-band bridge upgrades are available: the 2 W, 400 mW and 100 mW High Power Upgrade.  The 400 mW High Power Upgrade with the standard W-band resonator achieves pulse lengths (90o) of 16 ns.  While the 100 mW High Power Upgrade routinely achieves pulse lengths (90o) of 40 ns.
The benefits of the 400 mW High Power Upgrade are easily observed in the 4-pulse DEER Experiment.  The shorter pulse lengths lead to a higher signal to noise in the DEER spectrum which translates to a decrease in measuring time when compared to the longer pulses needed with the 100 mW High Power Upgrade.

More Informations


Service & Life Cycle Support for Magnetic Resonance and Preclinical Imaging

Bruker’s commitment to provide customers with unparalleled help throughout the buying cycle, from initial inquiry to evaluation, installation, and the lifetime of the instrument is now characterized by the LabScape service concept.

LabScape Maintenance Agreements, On-Site On-Demand and Enhance Your Lab are designed to offer a new approach to maintenance and service for the modern laboratory