Quadrupolar Pake pattern

At temperatures above 23 K the NMR line corresponds to a typical NMR quadrupolar Pake pattern with an asymmetry oitj = 0.2. The satellite pattern has completely disappeared. The width of the line decreases slowly with increasing temperature, which is an indication of a weakening of the T/ -bond between the metal and dihydrogen. 

The Pake pattern spectral shape is therefore preserved, but the 2H spectrum partly collapses to a narrower splitting due to the factor Sqd- The spacing of the maxima, the quadrupolar splitting Ag, is then given by... 

Fig. 12 2H spectra of HDPC-y-d6 on latex particles. The outer two maxima of each spectrum form the Pake pattern, while the central two narrow lines arise from free surfactant and HEX), respectively. The quadrupolar splitting is decreasing from a cationic towards an anionic environment (A to E). Figure taken from [41] with permission. 

Leopold et a/. (1982) observe two distinct deuterium lines, one of which is relatively narrow and one of which exhibits a resolved quadrupolar splitting. Figure 5 shows the Fourier transform of the echo observed after a 90° -t-90° pulse sequence in which the rf phase of the second pulse is 90° with respect to that of the first. The solid line in the 39 °K trace of Fig. 5 represents a calculated powder pattern of the broad (Pake doublet) component of the line. This component comprises 21 at. % of the sample. The... 

The line spfitting (shape) observed on the Pake-fike pattern, in the presence of molecular motions, depends on the geometry of motion (Fig. 2.20). This is due to the averaging of the quadrupolar parameters [126]. Molecular motion are classified with respect to the time scale of the quadrupolar cou-phng constant (Cq) [127] a number of models was proposed for describing the molecular motions one of the simplest is a cone model [128]. It must be stressed that variations in details of the geometry underlying the motional... 

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