Four regions of the propagation of the plume formed in pulsed laser deposition by optical-wavelength-sensitive CCD photography

Propagation of the plume formed by pulsed laser ablation of PbTiO3 in an am bient of oxygen and argon was studied by using a CCD camera. Two optical fi lters with different transmittance bands were used to distinguish the atomi c processes in the plume. The results show that, if a strong shock wave is formed, the propagation of the plume formed in pulsed laser deposition in o xygen ambient can be classified into four successive regions from the targe t to the substrate: (1) the plasma region nearby the target surface; (2) th e shock wave forming region in which the interactions between ablated speci es and ambient oxygen are not chemically reactive; (3) the shock wave propa gation region in which the excitations, dissociations, and ionizations, as well as gas-phase chemical reactions between ablated species and ambient ox ygen occur; and (4) sound wave region. (C) 2000 Elsevier Science S.A. All r ights reserved.