Very high frequency (263 GHz) pulse EPR spectroscopy of high spin transition metal centers
Abstract
Pulse Electron Paramagnetic Resonance (EPR) spectroscopy provides powerful tools for examining species with unpaired electrons, such as organic radicals and metal ions, in a wide variety of interesting systems. However, the lack of high power pulse amplifiers above approximately 100 GHz has limited its applicability at very high frequencies and magnetic fields. Here we describe the use of a new 10 W high frequency traveling wave vacuum tube amplifier employed in a pulse EPR spectrometer operating over a wide frequency bandwidth centered at 263 GHz. Very high frequency pulse EPR is of particular utility for studying spin S > 1/2 species, given that large broadening effects of “zero-field splitting” interactions often dominate EPR spectra obtained at low frequency. Improvements obtained at 263 GHz are illustrated for a series of high spin (S=5/2) Mn(II) complexes starting with Mn(II) impurities in a diamagnetic host up though Mn(II) bound in metal sequestering proteins. The instrument has sufficient mm-wave power to obtain high signal-to-noise electron spin echoes without a resonator, which offers a number of advantages as described herein.
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BibTeX
@article{hasanbasri2026very,
title = {{Very high frequency (263 GHz) pulse EPR spectroscopy of high spin transition metal centers}},
author = {Zikri Hasanbasri and Shasha Qiu and Guodong Rao and Amanda Caceres and Erica Debley and Yuan Zheng and Elizabeth M. Nolan and Marie Heffern and Paul Stucky and Neville C. Luhmann Jr and R. David Britt},
journal = {Nature Communications},
year = {2026},
month = oct,
doi = {10.1038/s41467-026-78076-w},
url = {https://www.nature.com/articles/s41467-026-78076-w},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Very high frequency (263 GHz) pulse EPR spectroscopy of high spin transition metal centers
AU - Zikri Hasanbasri
AU - Shasha Qiu
AU - Guodong Rao
AU - Amanda Caceres
AU - Erica Debley
AU - Yuan Zheng
AU - Elizabeth M. Nolan
AU - Marie Heffern
AU - Paul Stucky
AU - Neville C. Luhmann Jr
AU - R. David Britt
PY - 2026
DA - 2026/10/01
JO - Nature Communications
DO - 10.1038/s41467-026-78076-w
UR - https://www.nature.com/articles/s41467-026-78076-w
AB - Pulse Electron Paramagnetic Resonance (EPR) spectroscopy provides powerful tools for examining species with unpaired electrons, such as organic radicals and metal ions, in a wide variety of interesting systems. However, the lack of high power pulse amplifiers above approximately 100 GHz has limited its applicability at very high frequencies and magnetic fields. Here we describe the use of a new 10 W high frequency traveling wave vacuum tube amplifier employed in a pulse EPR spectrometer operating over a wide frequency bandwidth centered at 263 GHz. Very high frequency pulse EPR is of particular utility for studying spin S > 1/2 species, given that large broadening effects of “zero-field splitting” interactions often dominate EPR spectra obtained at low frequency. Improvements obtained at 263 GHz are illustrated for a series of high spin (S=5/2) Mn(II) complexes starting with Mn(II) impurities in a diamagnetic host up though Mn(II) bound in metal sequestering proteins. The instrument has sufficient mm-wave power to obtain high signal-to-noise electron spin echoes without a resonator, which offers a number of advantages as described herein.
SN - 2041-1723
ER -