Title: mm Wave (263 GHz) high power 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 high frequency traveling wave vacuum tube amplifier employed in a pulse EPR spectrometer operating over a wide frequency bandwidth centered at 263 GHz. This novel instrument provides significant improvements in sensitivity and resolution when compared to lower frequency instruments. 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.
Bio: R. David Britt, Winston Ko Chair in Science Leadership at UC Davis, has employed advanced electron paramagnetic resonance to study chemical/biochemical systems throughout his career, starting as a Physics Ph.D student at UC Berkeley where he built an early 9 GHz pulse EPR instrument for studying the oxygen evolving complex of Photosystem II. A core target of his EPR focus lies in the broad domain of “metals in biology”. His laboratory contains multiple continuous wave and pulse EPR spectrometers, including a new traveling wave tube-based high power pulse EPR spectrometer operating at 263 GHz. He is also the current chair of the Chemistry Department at UC Davis.
Host: Prof. Thomas Brunold