화학공학소재연구정보센터
Journal of Physical Chemistry A, Vol.124, No.46, 9617-9625, 2020
Using Mie Scattering to Determine the Wavelength-Dependent Refractive Index of Polystyrene Beads with Changing Temperature
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 degrees C) simultaneously. Polystyrene beads with a diameter of 2 mu m 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 1 54 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, lambda (0.480-0.650 mu m), and temperature, T, in centigrade, was found to be n = 1.5753 - (1.7336 X 10(-4))T + (9.733 x 10(-3))lambda(-)(2) in the temperature range 20 < T < 100 degrees C and n = 1.5877 - (2.9739 X 10(-4))T + (9.733 X 10(-3))lambda(-2) in the temperature range 100 < T < 234 degrees 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.