The bruker high-frequency-EPR system

Autor: A. Kamlowski, P. Höfer, D. Schmalbein, G. G. Maresch
Rok vydání: 1999
Předmět:
Zdroj: Applied Magnetic Resonance. 16:185-205
ISSN: 1613-7507
0937-9347
DOI: 10.1007/bf03161933
Popis: The design and performance of the first commercial 94 GHz continuous-wave (CW-)/Fourier transform (FT-) EPR and ENDOR spectrometer are described. The spectrometer design is based on a heterodyne microwave bridge using an X-band intermediate frequency (IF), a hybrid magnet system, a variable-temperature, top-loading TeraFlex probehead with a TE011 cavity as well as the ELEXSYS-line digital electronics and the Xepr software package. The W-band bridge can be driven by a CW- or pulse-IF unit and delivers a microwave power of 5 mW at 94 GHz. In pulse mode the power is sufficient for a π/2 pulse of 100 ns at a resonatorQ-value of 3000. The magnet system consists of a 6 T split-coil superconducting magnet and a water-cooled room-temperature coil. The main coil can be swept over the full range from 0 to 6 T. The room-temperature coil has a 800 G sweep range around the persistent field of the main magnet. The ENDOR probe features a tuned circuit for1H nuclei allowing an RF π-pulse of 8 μs with a 200 W amplifier. A broad-band setup is used for other nuclei. The E680 FT-EPR system utilizes the PatternJet pulse programmer and the SpecJet high-speed transient signal averager. The concerted action of these two devices results in a pulse EPR sensitivity equal or higher than in CW-EPR. Selected examples indicating the performance of the 94 GHz CW/FT-EPR and ENDOR systems are shown.
Databáze: OpenAIRE
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