Detection of acoustic waves by NMR using a radiofrequency field gradient.
A B(1) field gradient-based method previously described for the detection of mechanical vibrations has been applied to detect oscillatory motions in condensed matter originated from acoustic waves. A ladder-shaped coil generating a quasi-constant RF-field gradient was associated with a motion-encoding NMR sequence consisting in a repetitive binomial 13;31; RF pulse train (stroboscopic acquisition). The NMR response of a gel phantom subject to acoustic wave excitation in the 20-200 Hz range was investigated. Results showed a linear relationship between the NMR signal and the wave amplitude and a spectroscopic selectivity of the NMR sequence with respect to the input acoustic frequency. Spin displacements as short as a few tens of nanometers were able to be detected with this method.
Madelin
Guillaume
G
Magnetic Resonance Center, University of Rennes 1 and Centre Eugène Marquis, Rennes, France.
Baril
Nathalie
N
Lewa
Czeslaw J
CJ
Franconi
Jean Michel
JM
Canioni
Paul
P
Thiaudiére
Eric
E
de Certaines
Jacques D
JD
D000162:Acoustics; D004574:Electromagnetic Fields; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008954:Models, Biological; D019047:Phantoms, Imaging; D014465:Ultrasonics; D014732:Vibration