title: Narrow resonances and ripple fluctuations in light scattering by a spheroid.
abstract: We develop a semiclassical theory to explain the rapid ripple fluctuations in the extinction efficiency of light scattering by a transparent prolate spheroid. The theory is based on uniform asymptotic expansion of spheroidal radial functions. We have calculated the extinction efficiency for normal and oblique incidence. Our results suggest that the excitation of resonant electromagnetic modes inside a spheroidal particle is an important factor in the ripple structure. To verify this assumption and based on a Breit-Wigner formula, we develop a method to fit the peaks that appear in the spheroid's extinction cross section when some scattering parameters vary. In other words, our calculations suggest that narrow resonances are related to ripple fluctuations, whereas broad resonances contribute to extinction cross-sectional background.
authors.affiliation: Departamento Física, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, 36036-330, Juiz de Fora, Minas Gerais, Brasil.
authors.forename: André G
authors.initials: AG
authors.lastname: Simão
authors.forename: José P R F
authors.initials: JP
authors.lastname: de Mendonça
authors.forename: Rosana B
authors.initials: RB
authors.lastname: Santiago
authors.forename: Pedro C G
authors.initials: PC
authors.lastname: de Moraes
authors.forename: Paulo C
authors.initials: PC
authors.lastname: Soares
authors.forename: Luiz G
authors.initials: LG
authors.lastname: Guimarães