Formation of organosilicon nanoparticles in a gas aggregation source as witnessed by in situ light scattering
Abstrakt
In this work, we applied a method of light scattering for in situ detection of organosilicon nanoparticles (NPs). Plasma polymerization of hexamethyldisiloxane (HMDSO) in its 10 % mixture with Ar was used to synthesize the NPs by means of a gas aggregation cluster source (GAS).
The total pressure of 45 Pa and the RF discharge power in a range of 20 - 80 W were used. The GAS was constructed to allow passing of a laser beam (446 nm) across the beam of the NPs at the distance of 2 cm behind the exit orifice and acquiring the scattered light either by an optical emission spectrometer or by a CCD camera.
Although for 20 W power constant intensity of the scattered light was obtained, cycling instabilities were detected for higher power. Both amplitude and period of such fluctuations increased with the discharge power increasing from 40 to 80 W.
Cycling repelling of NPs and formation of plasma voids are suggested as possible mechanisms for the observed phenomena.