The initial step of particulate growth in a dust forming low pressure radio-frequency discharge has been studied in situ by laser induced ,particle explosive evaporation (LIPEE). With respect to the conventional light scattering, this method has been found much more efficient to observe small nanometer size particles, especially in the case of UV excimer laser radiation. Experimental results interpreted by a simple model of laser-particle interaction show that the intensity of LIPEE continuum emission depends on the particle radius roughly as y4. This interaction is essentially different Erom Rayleigh scattering, as the latter varies as y6. A study of time evolution of powder formation by LIPEE emission reveals the initial formation of nanometer size crystallites and the coalescence process leading to larger scale particles. It could be demonstrated that the critical step of dust formation is the initial clustering process leading to nanometer scale crystallites.
Study of Initial Dust Formation in an Ar-SiH4 Discharge by Laser Induced Particle Explosive Evaporation
DE GIORGI, Maria Luisa
1994-01-01
Abstract
The initial step of particulate growth in a dust forming low pressure radio-frequency discharge has been studied in situ by laser induced ,particle explosive evaporation (LIPEE). With respect to the conventional light scattering, this method has been found much more efficient to observe small nanometer size particles, especially in the case of UV excimer laser radiation. Experimental results interpreted by a simple model of laser-particle interaction show that the intensity of LIPEE continuum emission depends on the particle radius roughly as y4. This interaction is essentially different Erom Rayleigh scattering, as the latter varies as y6. A study of time evolution of powder formation by LIPEE emission reveals the initial formation of nanometer size crystallites and the coalescence process leading to larger scale particles. It could be demonstrated that the critical step of dust formation is the initial clustering process leading to nanometer scale crystallites.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
