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Wednesday, May 21, 2008

Interference from FM Radio Stations

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.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.

1 comment:

stan said...

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.