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1.
J Magn Reson ; 210(1): 126-32, 2011 May.
Artículo en Inglés | MEDLINE | ID: mdl-21444227

RESUMEN

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.


Asunto(s)
Espectroscopía de Resonancia por Spin del Electrón/métodos , Compuestos Ferrosos/química , Rubredoxinas/química , Anisotropía , Ácido Edético/química , Espectroscopía de Resonancia por Spin del Electrón/instrumentación , Diseño de Equipo , Sensibilidad y Especificidad , Soluciones/química , Marcadores de Spin
2.
J Magn Reson ; 173(1): 49-53, 2005 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-15705512

RESUMEN

A pulsed ENDOR spectrometer operating at a microwave frequency of 275 GHz is described. The results demonstrate that this type of spectroscopy can now be performed routinely at this high microwave frequency. The advantages compared to conventional EPR frequencies are the high spectral resolution, time resolution, and sensitivity.

3.
J Magn Reson ; 166(1): 92-9, 2004 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-14675824

RESUMEN

An electron paramagnetic resonance (EPR) spectrometer is described which allows for continuous-wave and pulsed EPR experiments at 275 GHz (wavelength 1.1 mm). The related magnetic field of 9.9 T for g approximately 2 is supplied by a superconducting solenoid. The microwave bridge employs quasi-optical as well as conventional waveguide components. A cylindrical, single-mode cavity provides a high filling factor and a high sensitivity for EPR detection. Even with the available microwave power of 1 mW incident at the cavity a high microwave magnetic field B1 is obtained of about 0.1 mT which permits pi/2-pulses as short as 100 ns. The performance of the spectrometer is illustrated with the help of spectra taken with several samples.


Asunto(s)
Espectroscopía de Resonancia por Spin del Electrón/instrumentación , Espectroscopía de Resonancia por Spin del Electrón/métodos , Microondas , Procesamiento de Señales Asistido por Computador/instrumentación , Carbono/química , Diseño de Equipo , Análisis de Falla de Equipo , Estudios de Factibilidad , Congelación , Óxido de Magnesio/química , Reproducibilidad de los Resultados , Sensibilidad y Especificidad , Óxido de Zinc/química
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