Wagner Robert, Benz Stefan, Möhler Ottmar, Saathoff Harald, Schnaiter Martin, Schurath Ulrich
Forschungszentrum Karlsruhe, Institute of Meteorology and Climate Research (IMK-AAF), Karlsruhe, Germany.
J Phys Chem A. 2005 Aug 18;109(32):7099-112. doi: 10.1021/jp051942z.
Complex refractive indices of supercooled liquid water have been retrieved at 269, 258, 252, and 238 K in the 4500-1100 cm(-1) wavenumber regime from series of infrared extinction spectra of micron-sized water droplets. The spectra collection was recorded during expansion experiments in the large coolable aerosol chamber AIDA of Forschungszentrum Karlsruhe. A Mie inversion technique was applied to derive the low-temperature refractive index data sets by iteratively adjusting the room-temperature optical constants of liquid water until obtaining the best agreement between measured and calculated infrared spectra of the supercooled water droplets. The new optical constants, revealing significant temperature-induced spectral variations in comparison with the room-temperature refractive indices, proved to be in good agreement with data sets obtained in a recent study. A detailed analysis was performed to elaborate potential inaccuracies in the retrieval results when deriving optical constants from particle extinction spectra using an iterative procedure.
通过微米级水滴的一系列红外消光光谱，在4500 - 1100厘米⁻¹波数范围内，已获取了269、258、252和238 K下过冷液态水的复折射率。光谱采集是在卡尔斯鲁厄研究中心的大型可冷却气溶胶室AIDA的膨胀实验期间记录的。应用米氏反演技术，通过迭代调整液态水的室温光学常数，直到过冷水滴的测量红外光谱与计算红外光谱达到最佳吻合，从而得出低温折射率数据集。与室温折射率相比，新的光学常数显示出显著的温度诱导光谱变化，事实证明与最近一项研究中获得的数据集吻合良好。当使用迭代程序从粒子消光光谱推导光学常数时，进行了详细分析以阐述检索结果中可能存在的不准确性。
