Multi-Frequency Resonators for CW & FT EPR

A unique solution for the demands in CW- and FT-EPR

The modular Flexline resonators are a unique solution for the demands in CW- and FT-EPR. They are the backbone of all pulse-EPR applications with the multi-frequency & multi-resonance ELEXSYS platform. A common feature of the Flexline probes is their high filling factor with correspondingly high sensitivity.

All Flexline resonators share the same cryogenics systems.

Dielectric Ring Resonator ER 4118X-MD5

The ER 4118X-MD5 is the universal probe of the ELEXSYS E 580 CW/FT-EPR X-Band spectrometer. It accepts sample tubes up to 5 mm O.D. and generates π/2-pulses of 10 ns at a bandwidth of 500 MHz. Due to its high filling factor it provides a high sensitivity even at the large bandwidth (low Q) required for FT-EPR spectroscopy.

Quick and easy sample changing is a standard feature at all temperatures even in high power operation. Ease of use is thereby greatly enhanced.

The resonator Q-factor can be changed continuously from very high to very low by varying the degree of coupling. This feature allows to match the resonator bandwidth to the specific experimental task, i.e. the lowest Q for the shortest dead-time and largest bandwidth, or a Q matched to the spin relaxation time for maximum signal-to-noise or critically coupled for CW-EPR.

The versatility is further enhanced by the (optional) optical window which allows irradiation of the total active resonator volume. The optical transparency is better than 90% in the range from 200 nm to 5 µm.

Pulse-ENDOR Resonator EN 4118X-MD4

This resonator is an integral part of the E 560D-P DICE pulsed ENDOR accessory. It provides a constant nuclear spin flip angle over a very large frequency range, greatly simplifying optimisation of the ENDOR signal and facilitating automated multiple dimension experiments. The EPR performance is as superior as with the ER 4118X-MD5 dielectric ring resonator. more...

Split Ring Resonators ER 4118X-MS5/3/2

The split ring resonators have been designed for special experimental requirements. They generate the highest B1, provide the largest bandwidth, have the highest sensitivity for the tiniest samples, feature the highest time resolution and the lowest dead-time. The ideal choice for:

  • Saturation Recovery EPR/ELDOR with CW detection
  • Transient Nutation spectroscopy of optically excited spins
  • Coherent Raman Beat (CRB) detection of ESEEM signals
  • DEER, DQC and ELDOR-NMR with up to 1000 MHz bandwidth
  • Nutation spectroscopy with up to 100 MHz microwave field strength

Three X-band Split Ring resonators ER 4118X-MS5/3/2 are available with maximum sample access of 5 mm, 3 mm and 2 mm respectively. 


Q-Band Pulse EPR & ENDOR Resonator EN 5107D2

Together with the ELEXSYS SuperQ-FT system, this resonator provides ideal tool for pulsed multiresonance EPR experiments at 34 GHz. more...

L- and S-Band Split Ring Resonators

The concept of the high filling factor is even more important for low frequency EPR. Therefore the Flexline design has been extended to L- and S-Band.

ER 4118L-MS5        L-Band module with 5 mm sample access

ER 4118S-MS5        S-Band module with 5 mm sample access


All Flexline probes are also available for CW-EPR with the EMX spectrometer series




Common features

  • available for L-, S- and X-Band
  • high filling factor and sensitivity
  • variable Q-factor for experiment optimisation
  • low dead-time for FT-EPR, ESEEM, DEER
  • integrated modulation coils for CW-EPR
  • optical window option  
  • temperature range 3.8 – 350 K compatible with ER 4118CV (N2) and ER 4118CF (He) cryostats

The common support holder for all modules allows easy and quick sample change under all operating conditions.

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