Discrete dipole approximation method for electromagnetic scattering by particles in an absorbing host medium

Abstract

Electromagnetic (EM) scattering by particles in an absorbing host medium is frequently encountered in practical applications, which makes the conventional EM scattering theory controversial and most of the theoretical methods for EM scattering inapplicable. Most of the relevant works in literature are confined to spherical particles. In this work, we develop the discrete dipole approximation (DDA) method for EM scattering by an arbitrary particle immersed in an absorbing host medium. We elaborate how the near- and far-field scattering quantities can be calculated by DDA. The accuracy of DDA is validated by comparison with the apparent and inherent scattering quantities of spherical particles computed by exact Mie theory. Then EM extinction by non-absorbing spheroids in absorbing host medium is studied by DDA. We find that particles that are prolonged in the incident direction are more likely to produce a negative apparent extinction, which is also supported by the near-field electric field distribution. The DDA method we develop will be useful and flexible in the study of EM scattering by particles in absorbing host medium.

Light scattering in TIRF microscopy: A theoretical study of the limits to surface selectivity

“…The central idea of DDA is to calculate light scattering induced by an arbitrarily sized and shaped dielectric object or set of such objects by replacing the actual object field with a finite array of induced dipoles, each responding to the applied field and to the combined scattered field of all the others at its location (26,27). The mathematics of this procedure, its generalization, and its implementation on a computer are continually being refined (28)(29)(30). Tractable DDA solutions require an array with enough array points to closely model the actual object and an appropriate array pattern distribution (not necessarily rectangular) to model sharp dielectric edges.…”

Computational Modeling of Chromatin Fiber to Characterize Its Organization Using Angle-Resolved Scattering of Circularly Polarized Light

“…The discrete dipole approximation (DDA) [ 47 , 48 , 49 ] method, the ADDA code [ 50 ], have been employed to compute angle-resolved scattering quantities. The DDA is a numerically exact method [ 51 ] and has successfully been employed to calculate various scattering quantities of different objects from micro- to nanoscale in biophysics [ 52 , 53 , 54 ] and plasmonics [ 55 , 56 , 57 ]. This method discretizes the scattering object into an array of polarizable point dipoles and considers the interaction of point dipoles.…”

Simulating Electron Energy-Loss Spectroscopy and Cathodoluminescence for Particles in Arbitrary Host Medium Using the Discrete Dipole Approximation

“…The same approach is commonly used, e.g., when defining cross sections for light scattering by particles in absorbing host medium. 43,44 Importantly, if separately measured W 0 is removed from the total Γ EELS (either by subtraction or deconvolution), it will also remove the ambiguity of the definition of W 0 in absorbing host medium. Thus, the particle-induced losses can be calculated fully rigorously even in this case, unless the electron beam intersects the particle.…”

“…In the case of a weak-coupling regime for the whole system (particle + slab of host medium), P EELS is equal to the difference between the losses in this system and the losses in the same system without a particle (both of which are potentially measurable). The same approach is commonly used, e.g., when defining cross sections for light scattering by particles in absorbing host medium. , Importantly, if separately measured W 0 is removed from the total Γ EELS (either by subtraction or deconvolution), it will also remove the ambiguity of the definition of W 0 in absorbing host medium. Thus, the particle-induced losses can be calculated fully rigorously even in this case, unless the electron beam intersects the particle.…”