High stability and low noise X-band FT EPR spectrometer with AWG unit and flexible open-source software for applications in pulse dipolar and hyperfine spectroscopy

Talk

  • FormatPoster
  • VenueX International Conference «High-Spin Molecules and Molecular Magnets» (MolMag 2023)
  • LocationNovosibirsk, Russia
  • Date

Abstract

Fourier transform (FT) experimental techniques have long been the standard for nuclear magnetic resonance. The situation is quite different in electron paramagnetic resonance (EPR), where progress is limited by the necessary advance in instrumentation. The frontiers of modern EPR spectroscopy are defined by home-built spectrometers that combine high microwave (MW) power with broadband excitation capability.

Herein, we describe two X-band EPR spectrometers designed for high stability and low noise FT measurements for applications in pulse dipolar and hyperfine spectroscopy, and spin relaxation. The first spectrometer is located at the Vorozhtsov Institute of Organic Chemistry and is equipped with all the necessary apparatus for conducting modern pulsed EPR experiments. The second is placed at the EPR spectroscopy endstation of the Novosibirsk Free Electron Laser and combines the use of MW and THz pulsed irradiation of the sample under study. The spectral resolution, dynamic range, and sensitivity of the spectrometers are benchmarked in several spectral and relaxation measurements of trityl and nitroxide radicals in solution and solid DPPH radical. The capabilities of broadband excitation are highlighted by SIFTER and 2D ESEEM measurements.

Along with the hardware characteristics of the spectrometer, the control software plays an equally important role in overall performance. The Atomize open-source modular software is used to control both spectrometers. The software allows the operator to observe the processed signal (after FT, phase cycling, etc.) in real time either for setting up the experiment (choosing magnetic field, adjusting pulse intervals, etc.) or for monitoring the progress of the experiment. In addition, embedded non-linear sampling makes many measurements more efficient.

This work was supported by the Russian Science Foundation 23-73-00042.