Hydrogen relaxation rates with

The Hill equation33 relates the T2 relaxation rate with the starch exchangeable hydrogen molar fraction and with the rate constant of... 

Proton and deuteron relaxation show that relatively slow hydrogen exchange occurs in neutral solutions. The exchange is, however, acid catalyzed. Rivkind interpreted increased spin-spin relaxation rate with increasing acidity as due to protonated vanadyl and estimated... 

N. Using the two measured cross-correlated relaxation rates, an apparent hydrogen bond length can be determined. Data for the 15N3-1H3...15N1 hydrogen bond in A-T base pairs of Antennapedia homeodomain DNA complex with a correlation time of 20 ns has been presented. 

The effective correlation times for an approximately isotropic motion, tr, ranged from 40.3 ps in methanol to 100.7 ps in acetic acid for 5a, and from 61.6 ps to 180.1 ps for 5b in the same solvents. Neither solvent viscosity nor dielectric constant bore any direct relationship to the correlation times found from the overall motion, and attempts to correlate relaxation data with parameters (other than dielectric constant) that reflect solvent polarity, such as Kosover Z-values, Win-stein y-values, and the like, were unsuccessful.90 Based on the maximum allowed error of 13% in the tr values derived from the propagation of the experimental error in the measured T, values, the rate of the overall motion for either 5a or 5b in these solvents followed the order methanol N,N-dimethylformamide d2o < pyridine < dimethyl sulfoxide. This sequence appears to reflect both the solvent viscosity and the molecular weight of the solvated species. On this basis, and assuming that each hydroxyl group is hydrogen-bonded to two molecules of the solvent,137 the molecular weights of the solvated species are as follows in methanol 256, N,N-dimethylformamide 364, water 144, pyridine 496, and dimethyl sulfoxide 312. 

The rate of the photobleaching relaxation of ultradispersed CdS, and hence the rate of the electron interfacial transfer from CdS to the surrounded media (finally, to protons yielding the hydrogen) appeared to depend on the size of the colloidal particles (see Fig. 2.10). The photobleaching relaxation rate increases as the size of the CdS semiconductor particles decreases. Such behavior may be caused by the increasing of reductive potential of photoexcited electron with decreasing size of semiconductor nanocolloids. In this case, according to the modern concepts of electron interfacial transfer reaction [19], the rate of electron transfer to the surrounded media should increase. 

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