Molecular Simulation of Carbon Ablation Using Beam Experiments and Resolved Microstructure

Kinetic model of adsorption on crystal surfaces

“…The surface layer is the last layer of atoms of the crystal located around z = 0 and constituted by free site particles C(s) as well as bulk crystal particles C(b). The unperturbed or standard surface layer distribution function f e σ is solution of the kinetic equation (8) where W σ = W s denotes the interaction potential between fixed interior crystal particles and crystal surface particles, m σ = m C , and J s,ph = J σ,ph the crystal particle and phonon collision operator. The standard surface distribution function f e σ may be seen as that of a physically unperturbed crystal surface.…”

“…Proceeding similarly for the standard surface distribution, it is also recovered that f (0) σ = f e σ is given by (19) with a number density of the surface layer n σ in the form (20) and the surface atoms are spatially distributed as exp(−W σ /k B T w ). The zeroth order solution f (0) σ = f e σ is furthermore the exact solution f e σ = n σ M σ of the thin layer equation since it is an exact solution of the full kinetic equation (8). The quantities n σ andn σ are characteristic of the crystal surface and its orientation and are related to the number of surface atoms per unit surface n σ = n σ dz.…”

“…The interaction of gases with solid surfaces is of paramount importance in science and engineering with applications in hypersonic reentry [1][2][3][4][5][6], combustion [7], ablation [8], condensation and evaporation [9][10][11], chemical deposition [12], catalysis [13], or corrosion [14]. This is a strong motivation for investigating kinetic models of adsorption processes, at a scale intermediate between molecular simulation [15][16][17] and fluid models [18][19][20], as well as deriving fluid boundary conditions at reactive surfaces by using the Chapman-Enskog method.…”

“…However, chemical bonds may also be formed between particles and the surface and these chemisorbed species have to be considered as other chemical species compared to their parents' gas phase. Such chemisorbed species play a fundamental role in surface chemistry, notably as active intermediate species in heterogeneous reaction mechanisms [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. A kinetic theory model describing both physisorption and chemisorption of gas particles on a solid surface is presented in this work.…”

Nanoscale oxidation behavior of carbon fibers revealed with in situ gas cell STEM

“…19,20 These ex-periments have led to the construction of a finite-rate kinetic model based on reaction probabilities. 21,22 Contrary to previous models which are largely based on empirical measurements, 23,24 all the individual rates are directly calculated from molecular beam data.…”