Inhomogeneity effects

Moreover, precession under selective irradiation occurs in the longitudinal plane of the rotating frame, instead of rotation in the transverse plane, which occurs during the evolution of the FID. The magnitude of the vector undergoing precession about the axis of irradiation decreases due to relaxation and field inhomogeneity effects. 

Spin-echo The refocusing of vectors in the xy-plane caused by a (t-180°-t) pulse sequence produces a spin-echo signal. It is used to remove field inhomogeneity effects or chemical shift precession effects. 

For practical applications, the inhomogeneity effect needs to be taken into account. For the effect of inhomogeneity associated with (dba, we can use... 

Pilinis, C., and X. Li, Particle Shape and Internal Inhomogeneity Effects on the Optical Properties of Tropospheric Aerosols of Relevance to Climate Forcing, J. Geophys. Res., 103, 3789-3800 (1998). 

Whilst it may not always be possible to use IDMS to assess the homogeneity of all materials for all analytes of interest, because of limited IDMS resource availability, the approach may be applied selectively to verify the suitability of bulk material preparation and subdivision procedures. Once IDMS has demonstrated that a particular bulk material preparation procedure is capable of producing material of sufficient homogeneity, the preparation procedure may be applied to similar material types without further IDMS measurements, but perhaps using more routine methodology to confirm that no gross inhomogeneity effects have unexpectedly occurred. 

Our current explanation can be summarized qualitatively in this statement [17] GGA favors both inhomogeneity and high density more than LSD does. These effects usually compete for example, inhomogeneity increases and density decreases as we stretch or break a bond. The inhomogeneity effect usually prevails but, for the bond length of H2, the density effect is large enough to carry the day. The final two sections of this article will quantify and test this statement. 

The spectra can further be interpreted to describe the excited-state dynamics [28b, d The advantage of our cold molecular jet experiment is that inhomogeneous effects are minimized. In absorption, all lines are lifetime broadened because of the efficient photochemistry of OCIO. The magnitude of this broadening does not depend on the rotational quantum numbers, but is strongly dependent on the... 

In general, the motion of M in the rotating frame follows from the classical torque exerted on it by Beff. The effect of an rf pulse is then to tip M away from the z axis and to generate a component in the x y plane. As viewed from the laboratory frame of reference, this component precesses in the xy plane and induces an electrical signal at frequency w in a coil placed in this plane. As the nuclear moments that make up M precess, they lose phase coherence as a result of interactions among them and magnetic field inhomogeneity effects, as described in Section 2.7. Thus Mxy decreases toward its equilibrium value of zero, and the... 

Despite numerous applications, conventional CRAMPS still remains one of the most demanding solid state NMR experiments as it requires the use of specially prepared spherical samples to minimise radiofrequency inhomogeneity effects and the careful calibration and setting of pulse widths and phases. Further modifications of the experiment that do not require the complicated and extended set-up procedures have been suggested recently. These are known as rotor-synchronised CRAMPS, which combines a new multiple pulse sequence [21], and its modification which uses a standard WHH-4 sequence at ultrafast MAS frequencies (e.g. 35 kHz) [22]. 

Efficiency of spin-locks. Examine the efficiency of Zj spin-locks on / and S rf channels using pulse sequences discussed elsewhere. The longest time for which the magnetization can be spin-locked on both channels depends on the strength of the rf power, stability of rf amplifiers, rf field inhomogeneity, effects of phase transients, span of the chemical shift, T p of the nuclei (assuming no spin-lock on the other channel), and the quality of the probe. In addition, on the /-spin channel, it also depends on the degree of suppression of the / / dipolar... 

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