Bloembergen—Purcell—Pound

Prom the pioneering BPP (Bloembergen-Purcell-Pound) formula (7), published in 1948 itself, it became immediately evident that, qualitatively speaking,... 

Carper, W. R., Wahlbeck, R G., Antony, J. H. et al., A Bloembergen-Purcell-Pound NMR relaxation study of the ionic liquid l-butyl-3-methylimidazo-lium hexafluorophosphate.. Anal. Bioanal. Chem., 378,1548, 2004. 

Rb and 1H SLR rate as a function of temperature is a very important parameter which shows the suppression of phase transition and reveals the frustration in the mixed system. Temperature dependence of Ti in any ordered system can be described by the well known Bloembergen-Purcell-Pound (BPP) type expression. However, disordered systems show deviations from BPP behaviour, showing a broad distribution of relaxation times. The magnetization recovery shows a stretched exponential recovery of magnetization following M(t)=Mo(1 — 2 exp (— r/Ti) ) where a is the stretched exponent. 

Here, K% is a constant related to the NMR coupling constant,. S 2 is the spectral density associated with the second-rank orientational correlation function g2(f). If g2(f) is an exponential function, such as in rotational diffusion, Eq. (16) reduces to the famous Bloembergen-Purcell-Pound (BPP) expression for the spin-lattice relaxation rate [81,82]. 

Meyer M, Maass P, Bunde A (1993) Spin-lattice relaxation nrai-Bloembergen-Purcell-Pound behavior by structural disorder and Coulomb interactions. Phys Rev Lett 71 573... 

Molten Salts. - The molecular structure and rotational motion of the ionic liquid l-butyl-3-methylimidazolium hexafluorophosphate ([BMIMJPFe]) were studied over a wide temperature range using the Bloembergen-Purcell-Pound... 

By combining several pulses and performing pulsed NMR measurements, spin-lattice relaxation time (Tj) and spin-spin relaxation time (T2) can be obtained. The NMR parameters can provide information on gel solvents and tiie microscopic molecular movement of polymers. When the relaxation is dominated by dipole-dipole interaction, the correlation time Xg of molecular motion from the relaxation time is based on the Bloembergen-Purcell-Pound (BPP) tiieory [90]. Examples of the structure and dynamics of polymer gels are described in what follows. 

There are two kinds of popular relaxation times, spin-lattice relaxation time and spin-spin relaxation time T2. Dipolar interactions between nuclear spins in polymers predominantly govern relaxation times. According to the Bloembergen-Purcell-Pound (BPP) theory [5], and T2 vary against the correlation time (t ) of the molecular motion, as indicated in Figure 8.1. Tj has the minimum at = 1/ , in which CO is the resonance angular frequency. If the Tj minimum is observed, the absolute correlation time of the molecular motion can be obtained. On the other hand, T2 decreases with an increment of From these behaviors of the relaxation times, the dynamics of polymer chain can be obtained. 

The rate of relaxation is affected by magnetic field fluctuations in the local environment of excited hydrogen spins. For simple liquids such as water, the diffusion of H2O molecules by Brownian motion allows H spins to encounter and interact with other dipole magnetic moments as described by the Bloembergen-Purcell-Pound, or BPP, theory (Bloembergen et al. 1948). In cementitious materials, there are two main sources of relaxation ... 

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