Light Scattering Model for the Total Internal Reflection Microscopy of Nonspherical and Inhomogeneous Particles

Kurzfassung

This chapter is devoted to the principles and applications of total internal reflection microscopy (TIRM), a near-field optical technique for probing particles and interfaces with nanometer-scale sensitivity. After recalling the fundamentals of diffraction and evanescent waves, we outline how TIRM exploits the exponentially decaying field created under total internal reflection to interrogate structures near a dielectric boundary. The theoretical framework is introduced in terms of scattering and absorption coefficients, phase functions, and extensions of Mie theory to evanescent illumination. Special attention is given to spherical and Janus particles, which highlight the role of asymmetry in scattering. A central theme of the chapter is the generation of TIRM images, both experimentally and through numerical modeling. Simulated images illustrate the dependence on particle size, refractive index, and separation distance, while analysis of the integral response across incident angles provides insight into sensitivity below and above the critical angle. Taken together, these results show how TIRM integrates optical theory and imaging to deliver quantitative information on nanoscale systems, making it a versatile tool for studying particle-surface interactions, soft matter, and biological interfaces.