Active cancellation - A means to zero dead-time pulse EPR

John M. Franck, Ryan P. Barnes, Timothy J. Keller, Thomas Kaufmann, Songi Han

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


The necessary resonator employed in pulse electron paramagnetic resonance (EPR) rings after the excitation pulse and creates a finite detector dead-time that ultimately prevents the detection of signal from fast relaxing spin systems, hindering the application of pulse EPR to room temperature measurements of interesting chemical or biological systems. We employ a recently available high bandwidth arbitrary waveform generator (AWG) to produce a cancellation pulse that precisely destructively interferes with the resonant cavity ring-down. We find that we can faithfully detect EPR signal at all times immediately after, as well as during, the excitation pulse. This is a proof of concept study showcasing the capability of AWG pulses to precisely cancel out the resonator ring-down, and allow for the detection of EPR signal during the pulse itself, as well as the dead-time of the resonator. However, the applicability of this approach to conventional EPR experiments is not immediate, as it hinges on either (1) the availability of low-noise microwave sources and amplifiers to produce the necessary power for pulse EPR experiment or (2) the availability of very high conversion factor micro coil resonators that allow for pulse EPR experiments at modest microwave power.

Original languageEnglish (US)
Pages (from-to)199-204
Number of pages6
JournalJournal of Magnetic Resonance
StatePublished - Dec 1 2015
Externally publishedYes


  • Active cancellation
  • Arbitrary Waveform Generation
  • Dead-time limited EPR
  • Pulse EPR

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Nuclear and High Energy Physics
  • Condensed Matter Physics


Dive into the research topics of 'Active cancellation - A means to zero dead-time pulse EPR'. Together they form a unique fingerprint.

Cite this