Field-frequency locked X-band Overhauser effect spectrometer

Chandrakumar, N. ; Narasimhan, P. T. (1981) Field-frequency locked X-band Overhauser effect spectrometer Review of Scientific Instruments, 52 (4). pp. 533-538. ISSN 0034-6748

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The design and construction of an Overhauser Effect Spectrometer operating at X band is described. The ESR section is a Varian V-4502 spectrometer equipped with a 9-in. electromagnet and a shim coil assembly. NMR detection is based on a broadband rf hybrid juction feeding a coil in an X-band quartz dielectric cavity. Signal processing is carried out at a constant intermediate frequency of 25.1 MHz with a Varian V-4311 fixed frequency rf unit. The mixing scheme employed to translate the NMR information to 25.1 MHz is described. Medium resolution performance (resolution ~10-6) for the NMR is achieved under field-frequency locked conditions. The lock is based on a Super-Regenerative Oscillator (SRO) housing a control sample, and operating as a field-tracking frequency source. This SRO injects into an oscillator which excites the analytical sample resonance and also serves as a local oscillator, thereby making the locked spectrometer multinuclear in capability. Typical Overhauser effect recordings of protons and fluorines are presented.

Item Type:Article
Source:Copyright of this article belongs to American Institute of Physics.
Keywords:Spectrometers; Microwave Radiation; Frequency Control; Design; Fabrication; Electromagnets; Nuclear Magnetic Resonance; Junctions; Cavities; Frequency Converters; Resolution
ID Code:24226
Deposited On:29 Nov 2010 09:24
Last Modified:09 Jun 2011 11:23

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