0000000000427083
AUTHOR
A. Tölle
Rotational diffusion of colloid spheres in concentrated suspensions studied by deuteron NMR
We present a study of the application of deuteron-nuclear magnetic resonance spectroscopy (NMR) to the investigation of the rotational diffusion of spherical colloidal particles. We performed NMR pulse experiments on colloidal suspensions of polystyrene latex spheres in water-glycerol mixtures in a wide range of particle volume fractions \ensuremath{\varphi} from the dilute suspension up to \ensuremath{\varphi}=0.504. We have analyzed the stimulated echo NMR signal in the time domain. The full shape of the orientational correlation function deviates from an exponential behavior in the whole \ensuremath{\varphi} range examined. We evaluate the rotational diffusion coefficient and calculate i…
Mode-coupling crossover in viscous toluene revealed by neutron and light scattering
The dynamics of supercooled toluene, studied in a GHz-THz range by incoherent neutron and depolarized light scattering, is found to be in full accord with mode coupling predictions. Around the susceptibility minimum, neutron spectra are wavenumber independent and proportional to light scattering data; the fast β-relaxation scaling law applies; amplitude and frequency diverge with power laws that extrapolate towards a crossover temperature Tc K.
Amorphous polymorphis in ice investigated by inelastic neutron scattering
Abstract High-density Ilda and low-density Ilda amorphous have been investigated by inelastic neutron scattering (INS) with emphasis on the energy window from 0.5 to 20 meV. At variance with earlier measurements the spectra in the Ilda phase show a simple ω2 behaviour in the acoustic region and the temperature dependence is found to be harmonic. Ilda converts with a strongly temperature-dependent rate towards Ilda ice. We have investigated in detail the time evolution of both the static and dynamic response functions at several temperatures. Elastic small-angle signals indicate the presence of strong heterogeneties at the early stages of the conversion process. At least two different time s…