Nutation frequency measurement

Nutation frequency measurement Peter Wu and Gottfried Otting have recently described a technique that can quickly and accurately yield the 90° pulse width via a single acquired transient. The concept is to measure the... 

Lyerla et al. measured Tic over a wide temperature range from room temperature down to 105 K [94], and concluded that Tic s of not only CH3 but also CH resonances depend on CH3 rotational motion, and that the broadening of the CH3 resonance below -100 °C is also due to modulation of CH3 rotational motion at the frequency of proton nutation in the presence of the decoupling field. Gomez et al. have also reported solid-state high-resolution 13C NMR spectra of isotactic polypropylenes [95]. They used samples characterized by X-ray crystallography and reconfirmed the results obtained by Bunn et al. 

The bifurcation scenario discussed above was actually observed in the experiment. Although a good qualitative agreement between theory and experiment was found [40], there are quantitative discrepancies. In the experiment, the measured onset of the nutation-precession motion turns out to be about 20% lower than predicted by theory. Moreover, the slope of the precession frequency versus intensity predicted by theory turned out to be different from that observed in the experiment. One of the two possible reasons could be the use of finite beam size in the experiment (that is typically of the order of the thickness of the layer), whereas in theory the plane wave approximation was assumed. Actually, the ratio 5 between diameter of the beam and the width of the layer is another bifurcation parameter (in the plane wave approximation, 6 oo) and was shown to play crucial role on the orientational dynamics [13]. There and in [44] the importance of the so called walk-off effect was pointed out which consists of spatial separation of Pointing vectors of the ordinary and extraordi-... 

This optical induction free decay can be measured with a beat technique at time r = 0 the frequency cu of a cw laser is switched from co = con to aJ o) 2 out of resonance with the molecules. The superposition of the damped wave at o) 2 emitted by the coherently prepared molecules with the wave at co gives a beat signal at the difference frequency Aco = co 2— o), which is detected [12.70]. If Aco is smaller than the Doppler width, the laser at cu interacts with another velocity subgroup of molecules and produces optical nutation, which superimposes the free-induction decay and which is responsible for the slowly varying envelope in Fig. 12.21b. 

A low RF power PISEMA pulse sequence, PITANSEMA, has been described for the measurement of heteronuclear dipolar couplings from solids." The method employs a time averaged nutation concept to significantly reduce the RF power required to spin-lock low frequency nuclear spins in PISEMA experiments. The efficacy of the 2D method is demonstrated on a single crystal of n-acetyl-L- N-valyl-L- N-leucine dipeptide to measure dipolar... 

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