Optical Charge Measurement at Nanoparticles in a Plasma

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In this project we will develop a novel, pure optical technique to address the charging ofnanometric (submicron) particles in a gaseous dusty plasma. The charging behavior of particles is a central and fundamental aspect of these plasmas. For this purpose, we will set up an optical diagnostic to measure the particle charge from the charge-dependent shift of phonon resonances in the infrared (IR) spectral regime. We will exploit that the optical phonon resonance of materials shifts with the charge on the dust surface towards higher energy (shorter wavelengths). The charge-dependent shift of the phonon resonance will be measured for different particle materials, particle sizes and particle properties, such as materials with positive and negative electron affinity, as well as for different plasma parameters. This allows the analysis of the charging dynamics of particles in a plasma and the fundamental and important properties of the plasma-particle interaction. The results can, in principle, be transferred to plasma-technological applications and astrophysical plasmas with nanoparticles.