Development of Absorption and Scattering Microspectroscopy Using a Phase-Stepping Method

Nanoparticles with subwavelength dimensions exhibit unique optical properties due to strong light-matter interactions and have received much attention in not only fundamental science but also applied science. The optical properties of the nanoparticles include both light scattering and absorption, and for practical applications, detailed knowledge of the scattering and absorption properties at the single nanoparticle level is indispensable. For this purpose, the development of a novel spectroscopic method for achieving simultaneous measurement of the absorption and scattering properties is desirable. The phase-stepping modulation technique enables the demodulation of a spectroscopic component for overlapped components and is promising for this purpose. In this study, we developed a novel spectroscopic technique by combining bright-field optical microscopy with a phase-step modulation method to simultaneously measure the absorption and scattering properties of nanoparticles.