Gas-nanoparticle scattering: a molecular view of momentum accommodation function.

We examine the origin of diffuse gas-particle scattering by molecular dynamics simulation and show that diffuse scattering is the consequence of gas molecule trapping on the particle surface. Trapping occurs because of gas-particle interactions and the particle's ability of energy accommodation. These observations explain the transition from specular-to-diffuse scattering as the particle size becomes larger than the molecular size. We discuss the implication of this transition on the transport properties of nanometer-size particles.