Bayreuth 1998 – wissenschaftliches Programm

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SYA: Symposium Kolloide Systeme und Polyelektrolyte

SYA 2: Kolloidale Systeme und Polyelektrolyte

SYA 2.4: Vortrag

Montag, 9. März 1998, 15:40–16:00, H18

Extinction and Scattering of Evanescent Waves by Small Particles - Analytical and Numerical Results — •A. Pack, M. Quinten, M. Hietschold, and R. Wannemacher — Institute of Physics, Chemnitz University of Technology, D-09107 Chemnitz

Mie theory has been employed to obtain cross sections for extinction and scattering of evanescent waves at small spherical particles on a glass surface. Comparison of the case of plane wave versus evanescent-wave excitation yields striking differences, which are explained by the enhanced contribution of higher multipoles in the case of evanescent waves. Strong enhancement of scattering as well as extinction effiencies for p-polarised waves as compared to s-polarisation is traced back to the weighting coefficients for the TE and TM multipole coefficients. Numerical studies of the same problem using the Multiple Multipole (MMP-) version of the Generalized Multipole Technique (GMT) are in excellent agreement with the analytical results. Scattering and extinction of small aggregates is also discussed. Wavelength-dependent cross sections are presented for silver particles as well as other materials. Applications to a recently developed differential interferometric scattering microscopy are discussed.