McGrory Megan R, King Martin D, Ward Andrew D
STFC, Central Laser Facility, Research Complex at Harwell, Rutherford Appleton Laboratory, Harwell Oxford, Didcot, Oxfordshire OX11 0FA, U.K.
Department of Earth Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, U.K.
J Phys Chem A. 2020 Nov 19;124(46):9617-9625. doi: 10.1021/acs.jpca.0c06121. Epub 2020 Nov 9.
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, , as a function of wavelength, λ (0.480-0.650 μm), and temperature, , in centigrade, was found to be = 1.5753 - (1.7336 × 10) + (9.733 × 10)λ in the temperature range 20 < < 100 °C and = 1.5877 - (2.9739 × 10) + (9.733 × 10)λ in the temperature range 100 < < 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.
聚苯乙烯珠粒常用于气溶胶科学中的测试颗粒。在此，报道了一种非接触技术，可同时测定固体气溶胶颗粒的折射率随波长和温度（20 - 234°C）的变化。直径为2μm的聚苯乙烯珠粒被光学捕获在陶瓷加热元件中心孔中的空气中，利用米氏光谱法测定了八个珠粒的半径和折射率（精度分别为0.8nm和0.0014）随加热和冷却的变化。在20 < < 100°C的温度范围内，折射率 随波长λ（0.480 - 0.650μm）和温度 （摄氏度）的函数关系为 = 1.5753 - (1.7336 × 10) + (9.733 × 10)λ；在100 < < 234°C的温度范围内，函数关系为 = 1.5877 - (2.9739 × 10) + (9.733 × 10)λ。该技术代表了在绝对测量材料折射率方面的一个重大进展，能够在很宽的温度和波长范围内高精度地进行测量。
