L. Boufendi et al., STUDY OF INITIAL DUST FORMATION IN AN AR-SIH4 DISCHARGE BY LASER-INDUCED PARTICLE EXPLOSIVE EVAPORATION, Journal of applied physics, 76(1), 1994, pp. 148-153
The initial step of particulate growth in a dust forming low pressure
radio-frequency discharge has been studied in situ by laser induced pa
rticle explosive evaporation (LIPEE). With respect to the conventional
light scattering, this method has been found much more efficient to o
bserve small nanometer size particles, especially in the case of UV ex
cimer laser radiation. Experimental results interpreted by a simple mo
del of laser-particle interaction show that the intensity of LIPEE con
tinuum emission depends on the particle radius roughly as r4. This int
eraction is essentially different from Rayleigh scattering, as the lat
ter varies as r6. A study of time evolution of powder formation by LIP
EE emission reveals the initial formation of nanometer size crystallit
es and the coalescence process leading to larger scale particles. It c
ould be demonstrated that the critical step of dust formation is the i
nitial clustering process leading to nanometer scale crystallites.