title: Continuous-wave EPR at 275GHz: application to high-spin Fe(3+) systems.
abstract: The 275GHz electron-paramagnetic-resonance spectrometer we reported on in 2004 has been equipped with a new probe head, which contains a cavity especially designed for operation in continuous-wave mode. The sensitivity and signal stability that is achieved with this new probe head is illustrated with 275GHz continuous-wave spectra of a 1mM frozen solution of the complex Fe(III)-ethylenediamine tetra-acetic acid and of 10mM frozen solutions of the protein rubredoxin, which contains Fe(3+) in its active site, from three different organisms. The high quality of the spectra of the rubredoxins allows the determination of the zero-field-splitting parameters with an accuracy of 0.5GHz. The success of our approach results partially from the enhanced absolute sensitivity, which can be reached using a single-mode cavity. At least as important is the signal stability that we were able to achieve with the new probe head.
authors: Department of Molecular Physics, Huygens Laboratory, Leiden University, The Netherlands. mathies@physics.leidenuniv.nl
authors: G
authors: G
authors: Mathies
authors: H
authors: H
authors: Blok
authors: J A J M
authors: JA
authors: Disselhorst
authors: P
authors: P
authors: Gast
authors: H
authors: H
authors: van der Meer
authors: D M
authors: DM
authors: Miedema
authors: R M
authors: RM
authors: Almeida
authors: J J G
authors: JJ
authors: Moura
authors: W R
authors: WR
authors: Hagen
authors: E J J
authors: EJ
authors: Groenen
mesh_terms: D016880:Anisotropy; D004492:Edetic Acid / Q000737:chemistry; D004578:Electron Spin Resonance Spectroscopy / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D005296:Ferrous Compounds / Q000737:chemistry*; D012416:Rubredoxins / Q000737:chemistry*; D012680:Sensitivity and Specificity; D012996:Solutions / Q000737:chemistry; D013113:Spin Labels
chemical_list: D005296:Ferrous Compounds; D012416:Rubredoxins; D012996:Solutions; D013113:Spin Labels; D004492:Edetic Acid