From 1 GHz to 263 GHz

Multi-Frequency CW-EPR

Disentangle magnetic field dependent from independent terms

Multi-frequency EPR is the tool to disentangle magnetic field dependent from independent terms. Bruker BioSpin's EPR product range currently encompass two orders of magnitude in microwave frequencies: 

  • L- and S-Band: 1 GHz and 3.5 GHz
  • X-Band: most common frequency at ca. 9.8 GHz
  • Q-Band : 34 GHz
  • W-Band: at 94 GHz
  • mm-wave: 263 GHz

While the advantages of high frequency EPR are obvious, low frequency EPR is the perfect choice for large samples and in particular in-vivo studies (ELEXSYS E540). 

Multi-frequency EPR spectra renders simulation much more effective. Also, motion effects can be studied over a wide temporal range.

Multi-frequency CW-EPR

The majority of CW-EPR systems operates at X-Band. Thus, the first step into multi-frequency CW-EPR is another operation frequency. In case of regular CW-EPR spectroscopy, Q-Band at 34 GHz is the best choice, because...

  • Q-Band provides a threefold higher Zeemann energy
  • Sample Size is still comparably large with 3 mm o.d.
  • Q-Band probes with optional window or ENDOR capabilities are available


The following table provides a list of the most common EPR frequencies with their frequency range and g=2 field value for radical species, respectively (cf. also What is EPR? CW EPR Theory). All these frequencies are commonly offered by our selection of magnet systems.

Microwave Frequency bands and Magnetic Fields

  L S X Q W
v / GHz 0.8-1.2 3.4-3.8 9-10 34 94
g = 2 / kG 0.35 1.3 3.4 12.2 33.5

Multi-frequency FT-EPR, ENDOR and ELDOR

Multi-frequency EPR by Bruker BioSpin is not limited to CW-EPR only. Bruker BioSpin's EPR products allow real multi-frequency and multi-resonance EPR, ENDOR and ELDOR both in CW- and Pulsed mode. For instance, thanks to the Intermediate Frequency (IF-) concept, an X-Band E580 system can readily be upgraded to Q-Band (SuperQ-FT).