FM radio stations transmit their signals at frequencies close to 100 MHz. Unfortunately this frequency is coincident with the resonance frequencies of several NMR active isotopes at commonly available magnetic field strengths. Under some circumstances, FM radio signals can interfere with NMR measurements. The figures below are solid state
27Al and
69Ga QCPMG NMR spectra taken in Windsor, Ontario in a 9.4 Tesla magnet. Both examples show interference from local FM radio stations. In the case of the
69Ga, no NMR signals are observed.
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Thank-you to
Joel Tang and
Robert Schurko from the
Department of Chemistry and Biochemistry at the
University of Windsor for providing the data for this post.
4 comments:
In support of these observations, may I draw attention to an April story by Vanni Piccinotti? Radio pollution is indeed nothing to laugh at in our field - and it is rapidly getting worse!
A time might come when new NMR installations will be dislocated hundreds of meters underground into abandoned potash mines (lucky you, since Canada has a lot of those :-)
If you are planning a new NMR lab,
EMI (electro-magnetic interference) is something you should take really seriously.
Nice blog, thanks for sharing such a nice blog.
Wouldn't it still be more economical to turn the NMR room into a Faraday cage?
Anonymous,
Radio interference in NMR spectra from radio stations is not that common. Building a Faraday cage around a large NMR lab would be very expensive.
Glenn
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