Molecular rotational resonance average-structure

As for all the systems relegated to Section 2 the attenuation function for structural H2O in the microwave and far-infrared region, as well as that for free H2O, can be understood in terms of collision-broadened, equilibrium systems. While the average values of the relaxation times, distribution parameters, and the features of the far-infrared spectra for these systems clearly differ, the physical mechanisms descriptive of these interactions are consonant. The distribution of free and structural H2O molecules over molecular environments is different, and differs for the latter case with specific systems, as are the rotational dynamics which govern the relaxation responses and the quasi-lattice vibrational dynamics which determine the far-infrared spectrum. Evidence for resonant features in the attenuation function for structural H2O, which have sometimes been invoked (24-26,59) to play a role in the microwave and millimeter-wave region, is tenuous and unconvincing. 

Chemical shifts of resonances obtained in solution NMR spectra have been routinely used for molecular structure identification and characterization of the organic solutes. In solution, the organic solutes undergo motion in all degrees of freedom including rotation and translation movement that is faster that the time scale of NMR measurement, viz. microseconds. As a result, the observed resonance is at the isotropic chemical shift, which is representative of the molecular structure and electronic environment averaged over all orientations with respect to the Bq (static magnetic field) direction. The relative intensities of the various resonances are usually representative of the relative mole fractions of the respective nuclei in the solution. 

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