Berlin 2014 – wissenschaftliches Programm

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P: Fachverband Plasmaphysik

P 1: Dusty Plasmas I

P 1.3: Vortrag

Montag, 17. März 2014, 11:25–11:40, SPA HS201

Absorption and scattering of infrared light by coated dielectric particles — •Elena Thiessen, Rafael L. Heinisch, Franz X. Bronold, and Holger Fehske — Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald, Deutschland

Extending our previous work [1,2] 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 and–eventually–as an electric probe with an optical read-out in general. 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. This resonance can be understood as the anti-bonding split-off of the anomalous resonance of the coat due to its mixing with a cavity mode supported by the core. The maximum of this resonance is in the far-infrared lessen thereby the requirements on the infrared instrumentation whereas the increased charge sensitivity opens the door to observe the charge-induced shifts already at the operation conditions typical for plasmas used to study self-organized dust structures.

[1] R. L. Heinisch et al., Phys. Rev. Lett. 109, 243903 (2012).

[2] R. L. Heinisch et al., Phys. Rev. E 88, 023109 (2013).