Reconstructing stochastic attractors from nanoscale experiments on a non-equilibrium reaction

in Physical Chemistry Chemical Physics (2018), 20(33), 21302--21312

We studied the catalytic NO2(g) + H2(g)/Pt system on model platinum catalysts with nanoscale spatial resolution by means of field emission microscopy (FEM). While the surface of the catalyst is in a non ... [more ▼]

We studied the catalytic NO2(g) + H2(g)/Pt system on model platinum catalysts with nanoscale spatial resolution by means of field emission microscopy (FEM). While the surface of the catalyst is in a non-reactive state at low H2 partial pressure, bursts of activity are observed when increasing this parameter. These kinetic instabilities subsequently evolve towards self-sustained periodic oscillations for a wide range of pressures. Combining time series analyses and numerical simulations of a simple reaction model, we clarify how these observations fit in the traditional classification of dynamical systems. In particular, reconstructions of the probability density around oscillating trajectories show that the experimental system defines a crater-like structure in probability space. The experimental observations thus correspond to a noise-perturbed limit cycle emerging from a nanometric reactive system. This conclusion is further supported by comparison with stochastic simulations of the proposed chemical model. The obtained results and simulations pave the way towards a better understanding of reactive nanosystems. [less ▲]

Interplay of chemical structure and magnetic order coupling at the interface between Cr2O3 and Fe3O4 in hybrid nanocomposites

in Physical Chemistry Chemical Physics (2014), 16(40), 22337-22342

Hybrid nanocomposites based on ferrimagnetic (FiM) Fe3O4 and magnetoelectric antiferromagnetic (AFM) Cr2O3 nanocrystals were synthesized to offer a particular three-dimensional (3D) interface between the ... [more ▼]

Hybrid nanocomposites based on ferrimagnetic (FiM) Fe3O4 and magnetoelectric antiferromagnetic (AFM) Cr2O3 nanocrystals were synthesized to offer a particular three-dimensional (3D) interface between the two oxides. This interface favours an intermixing process (demonstrated by combining Raman spectroscopy and magnetization measurements) that determines the final magnetic behavior. [less ▲]

Local chemical composition of nanophase-separated polymer brushes

in Physical Chemistry Chemical Physics (2011)

Using scattering scanning nearfield infrared microscopy (s-SNIM), we have imaged the nanoscale phase separation of mixed polystyrene–poly(methyl methacrylate) (PS–PMMA) brushes and investigated changes in ... [more ▼]

Using scattering scanning nearfield infrared microscopy (s-SNIM), we have imaged the nanoscale phase separation of mixed polystyrene–poly(methyl methacrylate) (PS–PMMA) brushes and investigated changes in the top layer as a function of solvent exposure. We deduce that the top-layer of the mixed brushes is composed primarily of PMMA after exposure to acetone, while after exposure to toluene this changes to top layers dominated by PS. Access to simultaneously measured topographic and chemical information allows direct correlation of the chemical morphology of the sample with topographic information. Our results demonstrate the potential of s-SNIM for chemical mapping based on distinct infrared absorption properties of polymers with a high spatial resolution of 80 nm . [less ▲]