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Conf’luence Pr. H. C. Chang

26 mai 2011

Polarization and Polaritons at Micro/Nanoscale Geometric Singularities

Lundi 30 mai à 10h30
Amphithéâtre Nougaro
Pr. H. C. Chang, l’Université Notre-Dame, Indianna

Résumé :
Molecular and interfacial forces are known to be anomalously amplified at sharp corners and at small scales. We report here a family of unique macroscopic phenomena due to dielectric, electron and ion polarization at micro-scale and nano-scale geometric singularities by dc/ac electric fields and by plasmonic electromganetic waves. For simple singularities like cones and wedges, local self-similar/spectral analyses of the local solution are sufficient to resolve the phenomena, without resorting to brute-force computations. Experiments guided by these theories have allowed us uncover/explain new physical phenomena, including surface charge effects on nanocolloid dielectrophoresis (PRE, 75, 060501, 2007), an interfacial AC cone with a half angle of 11 degrees instead of the classical 49 degree Taylor DC cone (PRL, 101, 204501 (2008)), nanojet and plume structures of DC/AC conic sprays, nanoslot/pore rectification (PRL, 103, 154502(2009)), nanocolloid/macroion dielectrophoresis to corners (Phys of Fluids, 14, 4315(2002)) and concentration at localized ion-depleted regions (ACSNano, 3, 1823(2009)), broadband plasmonic resonance at nanocones etc.