From CW-ENDOR to very advanced Pulsed ENDOR Techniques

ENDOR (Electron Nuclear DOuble Resonance), is an extremely valuable technique and can greatly simplify very complicated EPR spectra. Further, the resolution is enhanced with ENDOR if an EPR spectrum appears structureless due to inhomogeneous broadening.
The ELEXSYS DICE-II ENDOR systems provide the sound basis for state-of-the-art ENDOR spectroscopy by virtue of the DICE technology. DICE is the abbreviation for Digitally Computed Excitation offering FM, AM, FSK (Frequency Shift Keying) or field modulation and utilizing the Direct Digital Synthesis (DDS) concept for the E560D-P Pulsed ENDOR accessory.


Thanks to the FSK concept of the DICE-II system, even very high RF modulation amplitudes become accessible which is especially useful for broad ENDOR signals. EIE (ENDOR-induced EPR) and the optionally (special and general) TRIPLE further aid you in resolving complicated mixtures of spectra.
With ELEXSYS’ Xepr software, the acquisition of ENDOR, TRIPLE and EIE spectra becomes very easy, because all necessary parameters of the EPR and ENDOR experiment are linked to one another.

Pulsed ENDOR with the ELEXSYS E560D-P Accessory

Pulse ENDOR spectroscopy offers several distinct benefits for exploring nuclei coupled to the unpaired electron:

  • critical balancing of rf power vs. relaxation times is unnecessary
  • lower susceptibility to artifacts; no rf and no microwave fields are applied during the detection period
  • access to all relaxation times of a spin system (electron T1 & T2, nuclear T1 & T2, cross relaxation)
  • results complement those obtained from Electron Spin Echo Envelope Modulation (ESEEM)
  • the spin system can be manipulated to observe one particular property with high sensitivity and selectivity
  • the ENDOR effect can be as large as the electron spin echo itself

DICE is the abbreviation for DIgitally Computed Excitation, and the E560D-P accessory is based on Direct Digital Synthesis (DDS). The ultrafast switching ability of the DDS (on the nanosecond time scale) allows novel experimental techniques such as frequency bursts and fast RF phase switching.

The E 560D-P accessory comprises:

  • the acquisition server interface
  • a DDS ENDOR synthesizer (0.5 - 400 MHz)
  • a DDS TRIPLE synthesizer (0.5 - 400 MHz)
  • the rf frequency and phase switching unit
  • a matching network and 50 Ohm load
  • the Flexline pulsed ENDOR resonator
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