Coulomb crystal formation from growing particles in a plasma and the analysis

A Coulomb crystal formation process from growing particles in an ethylene plasma was analyzed simultaneously by Mie-scattering ellipsometry and charge-coupled device video images. It was confirmed that the phase transition of Coulomb liquid to Coulomb solid occurred after around 20 min of particle growth. The Coulomb crystal formed a body-centered-cubic (bcc) structure at the first stage, while it changed to a hexagonal pole structure after more than 40 min. Particles are collectively bound by cohesion forming a bcc structure. They are closely packed in lateral layers and aligned in the vertical direction when an attractive force between dipoles, which consists of negative particles and the polarized surrounding positive ions, becomes strong. (C) 1996 American Vacuum Society.