ON THE DETERMINATION OF THE EQUILIBRIUM SURFACE SEGREGATION ISOTHERMS FORM KINETIC MEASUREMENTS

Abstract. Thirty years ago, Lagües and Domange [1] studying dissolution and segregation kinetics, introduced the s urface local equilibrium hypothesis. This hypothesis is based on the idea that the kinetics (diffusion) is faster in the near surface region (selvedge) than in the bulk and thus it can be assumed that the atoms just below the selvedge can be in equilibrium with the atoms of the deposit. In this contribution, based on our recent work [2], using three dimensional kinetic Monte Carlo (KMC) and one dimensional kinetic mean filed (KMF) models, we show that the local equilibrium can be violated even in simple cases when complex surface phenomena (defects, relaxation, size effects, etc.) are not taken into account. Furthermore we illustrate that, even if the above hypothesis is obeyed, the determination of the surface segregation isotherms from kinetics can lead to uncertain result because of the restricted validity of Fick's first equation on the nanoscale

In Situ Optical Reflectance Difference Observations of CO Oxidation over Pd(100)

Quantum Matter and Optic

From dull to shiny: A novel setup for reflectance difference analysis under catalytic conditions

Catalysis and Surface Chemistr

Electrons, Photons, and Force: Quantitative Single-Molecule Measurements from Physics to Biology

Single-molecule measurement techniques have illuminated unprecedented details of chemical behavior, including observations of the motion of a single molecule on a surface, and even the vibration of a single bond within a molecule. Such measurements are critical to our understanding of entities ranging from single atoms to the most complex protein assemblies. We provide an overview of the strikingly diverse classes of measurements that can be used to quantify single-molecule properties, including those of single macromolecules and single molecular assemblies, and discuss the quantitative insights they provide. Examples are drawn from across the single-molecule literature, ranging from ultrahigh vacuum scanning tunneling microscopy studies of adsorbate diffusion on surfaces to fluorescence studies of protein conformational changes in solution