J. De Bleijser

On the single-molecule dynamics of water from proton, deuterium and oxygen-17 nuclear magnetic relaxation

Abstract Comparison of the nuclear relaxation rates of H, D and 17 O shows the isotropic motional model to be adequate for H 2 O on the picosecond timescale.

Long-range electric field gradients in charged polymer solutions as probed by 23Na relaxation

Bi-exponential 23Na nuclear magnetic relaxation is shown to be a general phenomenon in aqueous solutions of charged polymers in the semi-dilute region. Dependence on concentration, degree of polymerization, degree of ionization and presence of simple salt is established and discussed.

Nuclear relaxation and counterion behaviour in solutions of charged macromolecules. Correlation times from relaxation of I = 32 nuclei

Abstract From the relaxation of 23 Na in poly(methacrylic acid) solution at field strengths corresponding to 23 Na frequencies from 8 to 64 MHz, spectral densities in the range 0–128 MHz were derived. The results are used to discuss the uncertainties connected with current methods to determine correlation times from the nuclear relaxation of small ions in macromolecular solutions.

On the concentration dependence of the nature of polyelectrolyte solutions as detected by 23Na relaxation

Abstract Dependence of 23 Na nuclear magnetic relaxation on concentration and degree of polymerization is reported for solutions of Na polystyrenesulfonate. In the concentration range 10 −1 ⪯ c 10 −1 eq/e, 23 Na relaxation is far outside the extreme-narrowing limit and relaxation rates depend on the degree of polymerization. These phenomena seem to disappear outside this range.

On the structure and dynamics of water in AlCl3 solutions from H, D, 17O, and 27Al nuclear magnetic relaxation

The relaxation rates of 27Al, H, D, 17O, and the relaxation rate of H due to dipolar coupling to 17O were obtained in a series of aqueous AlCl3 solutions. From these data conclusions are reached about bulk water dynamics, the O–H bond distance, and the order within the Al3+ hydration shell. The bulk water dynamics is interpreted by a hydrodynamical model. For comparison viscosity data are presented. It is found that the change in the O–H distance of water molecules adjacent to Al3+ is significant and in agreement with reported theoretical results. The destruction of order within the Al3+ hexaquo complex with increasing concentration is indicated.

Water and aluminium self-diffusion in aqueous AlCl3 solutions

Abstract Self-diffusion coefficients of 27 Al and H 2 O were determined by the NMR pulsed-field-gradient method in a series of AlCl 3 solutions. From these data, bulk water self-diffusion coefficients are derived. It is shown that the relative influence on the bulk water translational motion agrees reasonably with the relative influence on the reorientational motion as reported in previous work. The bulk water self-diffusion is interpreted using a hydrodynamical model.

STEP-SCAN FT-IR PHOTOACOUSTIC SPECTROSCOPY : THE SIGNAL PHASE

The model of Rosencwaig and Gersho for the photoacoustic effect is tested. The use of carbon black samples as a phase reference to estimate the apparatus phase φapp from the experimental signal phase φexp turned out to be ambiguous. A new method is presented to correct the experimental signal phases φexp of polymer films for the apparatus phase φapp. The photoacoustic signal phase of some well-defined poly(ethyleneterephthalate) (PET) films is obtained. As a phase reference, transparent thermally thick polymer films were found to be more convenient and dependable than carbon black samples. The resulting phase spectra of thermally thick and thermally thin PET films confirm the Rosencwaig–Gersho theory.

Vibrational relaxation in hydrogen bonded systems: II. Experimental results

Experimental results are presented, supporting the theory presented earlier. These results, obtained by studying the shape of the as. OCO stretching band of acetate ions in CH3OH and deuterated analogs, show vibrational relaxation by near-resonant vibrational energy transfer to the solvent. The essential role of the H-bond in this process, as derived theoretically, is borne out by the results.

Vibrational relaxation in hydrogen bonded systems: I. Theory

Abstract A theory is proposed which expresses the influence of intermolecular interaction in H-bonded solutions on the solute IR band shape in terms of parameters characterising the modulation and strength of this interaction. It is found that appreciable vibrational relaxation can occur by interaction between oscillators with different frequencies, provided that the energy gap is closed by the hydrogen bond spectral density. Isotopic substitution of the solvent provides a means for experimental verification, which is the subject of a subsequent paper.

NUCLEAR MAGNETIC DYNAMIC SHIFT IN AN ISOTROPIC SYSTEM

Abstract The nuclear dynamic shift of 23 Na + in an aqueous system of crosslinked sodium poly (styrene sulfonate) has been determined at two field strengths. Also, the field dependence of the longitudinal and transverse relaxation rates was determined. The experimental values of the dynamic shift, which is directly related to the imaginary part of the spectral density, were found to be consistent with values calculated from the field dependence of the relaxation rates. It is explicitly shown that neglect of the dynamic shift in determining 23 Na relaxation rates from line shapes and spin-echo experiments is justified.