Using Mie Scattering to Determine the Wavelength-Dependent Refractive Index of Polystyrene Beads with Changing Temperature

作者：Megan McGrory, Martin D. King, Andrew D. Ward · 发表于：The Journal of Physical Chemistry A · 年份：2020 · DOI：10.1021/acs.jpca.0c06121 · 被引用次数：39 · 研究领域：Atmospheric aerosols and clouds、Atmospheric chemistry and aerosols、Indoor Air Quality and Microbial Exposure

High Resolution Image Download MS PowerPoint Slide Polystyrene beads are often used as test particles in aerosol science. Here, a contact-less technique is reported for determining the refractive index of a solid aerosol particle as a function of wavelength and temperature (20–234 °C) simultaneously. Polystyrene beads with a diameter of 2 μm were optically trapped in air in the central orifice of a ceramic heating element, and Mie spectroscopy was used to determine the radius and refractive index (to precisions of 0.8 nm and 0.0014) of eight beads as a function of heating and cooling. Refractive index, n, as a function of wavelength, λ (0.480–0.650 μm), and temperature, T, in centigrade, was found to be n = 1.5753 – (1.7336 × 10 –4 ) T + (9.733 × 10 –3 )λ –2 in the temperature range 20 < T < 100 °C and n = 1.5877 – (2.9739 × 10 –4 ) T + (9.733 × 10 –3 )λ –2 in the temperature range 100 < T < 234 °C. The technique represents a step change in measuring the refractive index of materials across an extended range of temperature and wavelength in an absolute manner and with high precision.