Spectral intensity correlations of backscattered diffuse light: the effect of scattering anisotropy.

In this work, we report experiments and a theoretical scheme of photon transport in the frequency domain of rigid turbid media. We have employed spectral multi-speckle intensity correlations to estimate optical properties as the transport mean free path and the absorption length of turbid systems. We propose a scheme based on the photon diffusion model using an effective path-length distribution in the backscattering configuration and take explicitly into account the particles scattering anisotropy parameter .

Time-resolved study of optical properties and microscopic dynamics during the drying of TiO films by spectral diffusing wave spectroscopy.

We present a combined experimental, theoretical, and numerical study of photon transport and microscopic dynamics in rigid and drying turbid thin films. Our setup is based in multispeckle diffusing wave spectroscopy and is adapted for frequency sweep of the illuminating source. We apply our approach to simultaneously monitor the changes in optical properties and microscopic dynamics of turbid thin films of rutile TiO powder dispersed in ethanol during the full drying process.

Effect of ionic strength on the aggregation kinetics of the amidated amyloid beta peptide Aβ (1-40) in aqueous solutions.

In this work we study the effect of solution ionic strength on the structural evolution of amidated amyloid beta peptide Aβ (1-40) oligomers at the early stages of fibril formation. By light scattering, we follow the time evolution of the structure and short-time dynamics of peptide structures at low ionic strengths. Our results allow identifying initial oligomer structures as the effective building blocks in the amyloid fibrils formation and indicate that the oligomers growth pathway, from compact structures to flexible chain-like structures, becomes faster as the solution ionic strength is increased.

Characterization of slow dynamics in turbid colloidal systems by a cross-correlation scheme based on echo dynamic light scattering.

We describe the implementation of echo dynamic light scattering in a cross-correlation detection scheme, which enables the study of slow dynamics in moderately turbid colloidal systems by adapting a commercial light scattering device. Our setup combines a 3D cross-correlation detection scheme (3DDLS), which allows for suppression of multiple scattering, with the speckle echo technique for dynamic light scattering. The recorded cross-correlation echoes provide precise ensemble-averaged results that appropriately describe sample dynamics of ergodic and non-ergodic colloidal systems of different turbidities.

Study of translational and rotational dynamics of birefringent colloidal particles by depolarized light scattering in the far- and near-field regimes.

We characterize the translational and rotational dynamics of birefringent spherical colloidal particles by depolarized light scattering in the far- and near-field regimes. For this purpose, we use depolarized dynamic light scattering and propose an extension of dynamic heterodyne near-field light scattering that takes into account the polarization state of the light. Such a combination of methods allows to access colloidal dynamics in an extended q-range and permits to evaluate different modes of particles motion in suspension.

Depolarization of backscattered linearly polarized light.

We formulate a quantitative description of backscattered linearly polarized light with an extended photon diffusion formalism taking explicitly into account the scattering anisotropy parameter g of the medium. From diffusing wave spectroscopy measurements, the characteristic depolarization length for linearly polarized light, lp , is deduced. We investigate the dependence of this length on the scattering anisotropy parameter g spanning an extended range from -1 (backscattering) to 1 (forward scattering).