Nutation angle

The classical cure 131,132), apart from special probe construction precautions, is a pulse sequence using a phase device detection cycle in which one exploits the fact that acoustic ringing increases linearly with pulse width while NMR signal follows the sinusoidal nutation-angle curve. In its most elementary form, the cycle is composed of four steps (ideally with null 5) ... 

Fig. 4. Signal amplitude as a function of excitation pulse nutation angle for nuclear quadrupole resonance (NQR) of a powder sample (solid line) and single crystal (dotted line).

M/tan0 for various 6 values to yield a straight line with a slope exp(-At/Tj) for magnetization obeying exponential recovery. In this case, the pulse interval At is fixed and the adjustable parameter is the nutation angle which is most conveniently changed by the rf pulse width. This may make the method awkward for most existing apparatus. 

R. K. Gupta, "A new look at the method of variable nutation angle for the measurement of spin-lattice relaxation times using Fourier transform NMR," J. Magn. Resonance 25, 231-235 (1977). 

The angle is usually called the nutation angle and the precession angle. The Euler angles can be expressed by the functions p, q T a P introduced above. By a direct calculation it can be found that... 

It is important to note that the recycle delay can be chosen to be shorter if pulses with nutation angles lower than nil are employed, which can lead to a substantial time saving. For given values of recycle delay ( and T, the optimum flip angle is known as the Ernst-Anderson angle (0op [19] ... 

A new method for the simultaneous suppression of water and lipid resonances using a series of dual-band frequency-selective radiofrequency pulses with associated dephasing gradients is presented." By optimizing the nutation angles of the individual pulses, the water and lipid suppression is... 

Figure 2.3 The effects of the RF field Bj on the nuclear magnetization is to drive the magnetization vector away from the z-axis towards the transverse plane. Depending on the amplitude and duration of the RF pulse one can have a njl pulse, a it pulse, or, more generally, a pulse with a nutation angle Qp.

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