Evolution of size and charge of sodium nanoparticles in an electro-opticaltrap

Single and small numbers of sodium nanoparticles were studied in a cold pla sma environment of a modified quadrupole trap (optical + low-frequency elec trical field). The single nanoparticle radius (mass) was first determined b y observing its Brownian motion. Particle size evolution (similar to 90-510 nm) was then determined by applying Mie theory calculations to the intensi ty of light scattered by a small number of nanoparticles. The trapping potential was determined using a two-nanoparticle system as a probe. As a result, the electrical charge of the nanoparticles and its evol ution (similar to 200-1000 elementary charge units) was also found. Strong depolarization of one-nanoparticle scattered light was observed.