International audienceIn this paper we put on solid ground the optical time-resolved study of spin-state photoinduced switching in an Fe(III) compound whose structural dynamics have been recently unveiled. We provide the experimental evidence of complex dynamics, occurring in succession, and spanning ten decades in time. We show that in addition to the ultrafast photoinduced molecular switching occurring on the subpicosecond timescale, there exists two additional switching processes significantly affecting the fate of the macroscopic material: one driven by elastic interactions as volume expansion occurs on a tens of nanoseconds timescale, and another one associated with heat diffusion and thermal switching taking place on a tens of microseconds timescale

International audienceWe present an experimental apparatus specifically designed to investigate the precursors of failure in granular materials. A sample of granular material is placed between a latex membrane and a glass plate. A confining effective pressure is applied by applying vacuum to the sample. Displacement-controlled compression is applied in the vertical direction, while the specimen deforms in plane strain. A Diffusing Wave Spectroscopy visualization setup gives access to the measurement of deformations near the glass plate. After describing the different parts of this experimental setup, we present a demonstration experiment where extremely small (of order $10^{-5}$) heterogeneous strains are measured during the loading process

A bamboo foam is the simplest case of an ordered foam confined in a narrow channel. It is made of a regular film distribution, arranged perpendicularly to the channel. Our work consists of studying the structural properties of several films taken in a drained foam. X-ray experiments highlighted the equality of the equilibrium thickness for each film within a foam. The same thickness was found as by measurements of disjoining pressure isotherms, proving as well that films of a bamboo foam behave like isolated ones. The refinement of X-ray data by a simple model of specular reflectivity showed a significant variation of the electronic distribution of the surfactant layer for a common black film forwarding from one equilibrium state to another. A discussion on the organization of the surfactant molecules to the gas/liquid interface and film is proposed.