Shaped optimal control pulses for increased excitation bandwidth in EPR

Philipp E. Spindler, Yun Zhang, Burkhard Endeward, Naum Gershernzon, Thomas E. Skinner, Steffen J. Glaser, Thomas F. Prisner

Research output: Contribution to journalArticlepeer-review

109 Scopus citations

Abstract

A 1 ns resolution pulse shaping unit has been developed for pulsed EPR spectroscopy to enable 14-bit amplitude and phase modulation. Shaped broadband excitation pulses designed using optimal control theory (OCT) have been tested with this device at X-band frequency (9 GHz). FT-EPR experiments on organic radicals in solution have been performed with the new pulses, designed for uniform excitation over a significantly increased bandwidth compared to a classical rectangular π/2 pulse of the same B1 amplitude. The concept of a dead-time compensated prefocused pulse has been introduced to EPR with a self-refocusing of 200 ns after the end of the pulse. Echo-like refocused signals have been recorded and compared to the performance of a classical Hahn-echo sequence. The impulse response function of the microwave setup has been measured and incorporated into the algorithm for designing OCT pulses, resulting in further significant improvements in performance. Experimental limitations and potential new applications of OCT pulses in EPR spectroscopy will be discussed.

Original languageEnglish
Pages (from-to)49-58
Number of pages10
JournalJournal of Magnetic Resonance
Volume218
DOIs
StatePublished - May 2012

Keywords

  • Excitation bandwidth
  • FT-EPR
  • Optimal control theory
  • Pulse electron paramagnetic resonance
  • Shaped pulses

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