Positive-intrinsic-negative diode-based duplexer for microcoil nuclear magnetic resonance

Microcoil nuclear magnetic resonance (NMR), using receiver coils of diameters of order 100 μm, is increasingly employed to observe very small (∼0.3 nl) samples with high sensitivity. However, many experimental aspects of microcoil NMR differ greatly from conventional NMR. In particular, the duplexer...

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Bibliographic Details
Published in:Review of scientific instruments 2000-07, Vol.71 (7), p.2908-2913
Main Authors: Seeber, D. A., Hoftiezer, J. H., Pennington, C. H.
Format: Article
Language:English
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Summary:Microcoil nuclear magnetic resonance (NMR), using receiver coils of diameters of order 100 μm, is increasingly employed to observe very small (∼0.3 nl) samples with high sensitivity. However, many experimental aspects of microcoil NMR differ greatly from conventional NMR. In particular, the duplexer is a device used to switch between the transmit and receive phases of the experiment. The conventional duplexer is a passive device employing crossed diodes, that switch automatically to transmit mode when high rf power is present. In microcoil NMR, however, the transmitter power is necessarily quite low, with voltages that do not greatly exceed characteristic diode voltage drops. Here we present the complete design and construction methods for a duplexer well suited to the special demands of microcoil NMR.
ISSN:0034-6748
1089-7623
DOI:10.1063/1.1150710