Local monitoring of proton spin diffusion in static and rotating samples via spy detection
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Analytical descriptions of (multiple-contact) cross-polarization dynamics and spin-lattice relaxation in solid alanine
2023, Journal of Magnetic Resonance Open<sup>13</sup>C/<sup>19</sup>F high-resolution solid-state NMR studies on layered carbon-fluorine compounds
2018, CarbonCitation Excerpt :The spin-diffusion time t is assumed roughly to be ca. 0.1 s from the observed 2D 19F-19F exchange cross peaks for F2-F3 (Fig. 6) under MAS with νR = 35 kHz. As the spin-diffusion time is scaled as 1/νR by MAS [43,44], we estimate the spin-diffusion time for the static case to be ca. 3 × 10−3 s. The diffusion constant D for 19F-19F spin diffusion was ca. 7 × 10−12 cm2s−1 for static CaF2 [45].
Sensitivity enhancement by multiple-contact cross-polarization under magic-angle spinning
2017, Journal of Magnetic ResonanceBasic principles of static proton low-resolution spin diffusion NMR in nanophase-separated materials with mobility contrast
2015, Solid State Nuclear Magnetic ResonanceCitation Excerpt :We have performed similar experiments [46,47], restricting ourselves to rather localized hole burning using Lee–Goldburg CP [50,51], see Fig. 12a and b. This strategy is similar to the one of Ernst and coworkers [44], and is advantageous in that it simplifies the data analysis (see below). It also allows for a second phase-inverted LGCP step that can be used to double the experimental contrast by nearly inverting rather than just nulling the 1H hole magnetization (Fig. 12b).
Moderate MAS enhances local <sup>1</sup>H spin exchange and spin diffusion
2015, Journal of Magnetic ResonanceCitation Excerpt :Without decoupling of the 13C spins during the spin diffusion delay, PE’s short-range spin-diffusion rate is found to be only (63 ± 1)% of the value observed when applying 13C decoupling. Reduced spin diffusion coefficients due to the presence of 13C spins were already noticed [27,28], however, as we will discuss in more detail below, the extent to which 1H spin diffusion is reduced by presence of the 13C spins should be rather sensitive to experimental details: the more local the probe of the 13C spin environment, the higher its impact on proton spin diffusion. The decreased efficiency of spin diffusion in the absence of 13C decoupling stresses the sensitivity of spin diffusion to local disturbances, which in turn supports the observation that local-scale spin diffusion is, on average, less effective than spin diffusion over larger distances.
Monitoring nuclear spin-flip processes and measuring spin-diffusion constants via hole burning into the magnetization
2012, Chemical Physics LettersCitation Excerpt :Except for the measurement comparing single (Figure 1a) and double (Figure 1b) hole burning, experiments have been performed using the pulse sequence presented in Figure 1b. A procedure called spy detection, which is similar to th one presented here, was introduced by Zhang, Meier and Ernst [9]. They used a single crystal of ferrocene along with a Hartmann–Hahn contact to transfer net polarization from rare spins to abundant spins.