Measurement the spin-lattice relaxation time

Figure 1.40 Stacked plots of H-NMR spectra for ethylbenzene. This experiment can be used to measure the spin-lattice relaxation time, T].

Morrow et al. measured the spin-lattice relaxation time Ti and quadrupole echo decay times T ) of headgroup deuterated d4-DMPC as a function of temperature and pressure to yield additional information about changes in the headgroup dynamics. Generally, motions in a LC phospholipid bilayer can... 

Aso et al. (40) examined the molecular mobility of sucrose and polyvinylpyrrolidone in 1 1 lyophilized mixtures by measuring the spin-lattice relaxation times (7)) of individual carbon atoms by NMR for systems containing residual moisture at varying levels. 7) of the pyrrolidone ring carbon increased with residual moisture for lyophilized PVP alone. However, the mobility of these carbons did not increase with residual moisture when PYP was colyophilized with sucrose. Similarly, the mobility of sucrose did not increase with water activity as much in sucrose/PVP mixtures as much as in sucrose alone. Inhibition of sucrose crystallization by PVP in the presence of water appears to be linked to the effect of PVP on the molecular mobility of sucrose. 

The spin-lattice rehucation times Ti are measured by the inversion-recovery method By the capillary method, we have measured the spin-lattice relaxation times Tj for heavy water (D2Q) over a wide range of temperature. The results are in good agreement with those given by Hindman and co-workers - within the expe ental uncertainties our and their uncertainties ate 1% and 12%, respectively. The uncertainty of tempm ture is 0.1 C in the present work. 

Spin-Lattice Relaxation. In order to determine whether each resonance line comprises a single component, we first measured the spin-lattice relaxation time Tic by the pulse sequence developed by Torchia [53] or by the standard saturation-recovery pulse sequence. The Tic values thus obtained were 2560,263 and 1.7 s for resonance line I and 0.37 s for line II. As reported by several investigators, the line at 33 ppm is associated with three different Tic values [ 17,54,55]. This means that this line is contributed to by three components with different molecular mobilities. However, since each component was represented by a single Lorentzian line shape at 33 ppm, they are all assignable to methylene groups in the orthorhombic crystalline form or in the trans-trans conformation. The component with a Tic of s can be assigned to methylene groups with a some-... 

The blending effects on motion have also been studied by measuring the spin-lattice relaxation time T. Feng et al. [70] measured Ti of PPO and PS in PPO/PS. They showed that the respective values for the... 

The observation of rigid and mobile phases in 15N enriched melamine-formaldehyde resins makes it possible to measure the spin-lattice relaxation times in both regions. By using standard inversion recovery and cross-polarization (86) T pulse sequences the values in the range 6-22 s and 25-69 s, respectively, were obtained for the secondary amine resonance. Shorter relaxation times in more mobile portions of the sample, as well as longer times in more rigid parts, show a similar temperature dependence with a possible minimum (around 343 K) associated with relaxation processes in the resin (53). 

The concentrations of Components 7 and 9 in Experiment 10 were verified by integration of the carbonyl resonances. In order to do this it was necessary to measure the spin lattice relaxation times (Ti) (12) of the carbonyl carbons. These were 5.8 sec in 7 and 6.3 sec in 9. The spectrum in Experiment 10 was then reaccumulated, using a 60-sec repetition rate, and integrated. The calculated and observed integral ratios were within the limits of the experimental error. 

We measured the spin-lattice relaxation time Ti by using the standard tt-t-tt/2 sequences. As an example of inversion recovery kinetics, results for (MA-St)n in the coil form at otj = 0.87 and 35 C is shown in Figure 7, where the delay time between 180° and 90° pulses is shown. At a glance, it is understood that both the Tj-values of the side chain and backbone protons do not coincide with each other. The Tj can simply be calculated by the null-method.34 However, it is prefered to calculate it by use of the following general formulae of inversion recovery kinetics under an assumption of single exponential decay function ... 

Experimental Methods of Measuring the Spin-Lattice Relaxation Time... 

Dangling bonds related to structural defects in a DND particle have a nonzero spin and are revealed with the use of the EPR and NMR (nuclear magnetic resonance) techniques by measuring the spin-lattice relaxation times. Their number is estimated as 1-40 per one DND particle. Experiments performed with copper ions deposited on the surface of DND particles suggest that these defects are located inside the particle at a distance of 0.8-1.5 nm from its surface. ... 

The NMR of Tm has also been studied in single crystal TmES. Since in this case the lowest ionic level in the CEF potential is a singlet, the magnetic hyperfine interaction vanishes in first order (section 2.2.3.1) enabling conventional NMR to be observed. In addition, Tm has spin so that quadrupole effects are not involved. Teplov (1969) investigated the Tm NMR in single crystal TmES at low temperatures, and Al tshuler (1969) measured the spin-lattice relaxation time Ti, also at low temperatures. 

A Fourier-transform method has been used to measure the spin-lattice relaxation times (Ti-values) of the anomeric protons of a selection of di-, oligo-, and polysaccharide derivatives ie.g. cellobiose, maltose, gentiobiose, maltotriose, and a- and j8-Schardinger dextrins). Differences in the Ti-values of the anomeric protons were found for each of the disaccharides examined, the anomeric proton of the non-reducing residue having a smaller 71-value in each case - for cellobiose,... 

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