Infrared light extinction by charged dielectric core-coat particles

We study the effect of surplus electrons on the infrared extinction of dielectric particles with a core-coat structure and propose to use it for an optical measurement of the particle charge in a dusty plasma. The particles consist of an inner core with negative and an outer coat with positive electron affinity. Both the core and the coat give rise to strong transverse optical phonon resonances, leading to anomalous light scattering in the infrared. Due to the radial profile of the electron affinity electrons accumulate in the coat region making the infrared extinction of this type of particles very charge-sensitive, in particular, the extinction due to a resonance arising solely due to the core-coat structure. The maximum of this resonance is in the far-infrared and responds to particle charges realizable in ordinary dusty laboratory plasmas.Comment: 12 pages, 8 figure

Physisorption kinetics of electrons at plasma boundaries

Plasma-boundaries floating in an ionized gas are usually negatively charged. They accumulate electrons more efficiently than ions which leads to the formation of a quasi-stationary electron film at the boundaries. We propose, in a colloquial manner, a physisorption-inspired quantum-kinetic description of the build-up of surface charges at inert plasma boundaries and calculate the electron sticking coefficient and the electron desorption time, which play an important role in determining the quasi-stationary surface charge, and about which little is empirically and theoretically known, from a microscopic model for the electron-wall interaction. In an exploratory calculation we specifically consider a metallic boundary. But thereby we identify quite generally what we believe are the key issues of the electronic microphysics at inert plasma boundaries in the hope to inspire other groups to join us on our journey.Comment: accepted version, 30 pages, 14 figure