Nanoparticle growth optimization for the study of the electron photodetachment*

We report on the optimization of the nanoparticle growth process by varying argon/acetylene gas mixture ratios and gas pressure in a radio frequency (RF) capacitively coupled plasma. The growth of the dust particles is monitored by measuring a DC self-bias voltage of the RF discharge and analyzing the optical emission spectroscopy data. This dusty plasma setup was developed for studies of a laser-stimulated photodetachment of electrons (LSPD) from negatively charged dust particles. The LSPD was tested for electron photodetachment from a quartz surface charged negatively in the DC plasma environment. A dye laser with 620 nm (~2,0 eV photon energy) pumped by the Nd: YAG laser (532nm, 10 Hz, and ~8 ns pulse width) generates the photon flux to the charged surface. A contactless electrostatic voltmeter is used to monitor the potential of the quartz surface after its charging in the plasma and the LSPD. The surface potential drops after the LSPD is applied to the charged surface. The surface potential was monitored during the different number of applied subsequent laser pulses and the surface potential decay showed nonlinear behavior with a faster drop after the initial pulses. Also, it was found that the measured drop in the surface potential is highly sensitive to surface contamination.