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Melodies, General Remarks

Once the auditory presentation of FIDs became established in the early seventies, it is save to assume that many an operator was tempted getting melodies out of an NMR spectrometer. Pulse programmers with settable carrier offsets were not yet available at that time, and melodies with fixed tone intervals had to be created by trial-and-error turning of the field (Z0) wheel. Presumably, this was a quite disappointing approach and many an operator quit after a few attempts.

We are nowadays (1996) able to exactly program frequencies and delays, and to rapidly scan these pulse sequences on NMR spectrometers, in the very same way as music sequencers perform. Of course, the prize we have to pay is the "inhuman feeling" of the obtained melodies, both on spectrometers and on sequencers...

Playing monophonic melodies is comparatively easy: a sample consisting of a single resonance line in the spectrum must be employed (in the present case: acetone in CDCl3). Next, the carrier frequency has to be shifted in the pulse program, along with appropriate delays according to the song's demands.

Playing polyphonic melodies is more tricky. You will learn how this is done in the headers of the involved examples.

You may listen to and look up the pulse sequences of the following melodies:

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August 20, 1996