magnetic resonance

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The phenomenon of absorption of certain frequencies of radio and microwave radiation by atoms placed in a magnetic field. The pattern of absorption reveals molecular structure.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Physics) A phenomenon resulting from quantization in the magnetic field of electrons or atoms or molecules or nuclei exposed to an external magnetic field, by which a narrow frequency band of radio waves may be absorbed and re-emitted by the object.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun resonance of electrons or atoms or molecules or nuclei to radiation frequencies as a result of space quantization in a magnetic field