Fuller K A, Downing H D, Querry M R
Appl Opt. 1991 Oct 1;30(28):4081-93. doi: 10.1364/AO.30.004081.
Because of recent developments in planetary astronomy, there has been a resurgence of interest in the optical and thermodynamic properties of elemental sulfur. An encounter between the space probe Galileo and the Jovian moons, particularly Io, is expected to contribute further to this interest. A thorough investigation of the optical properties of orthorhombic sulfur from 2 to 56 microm (5000-180 cm(-1)) is presented. Since less care was taken in many past studies of this element than was warranted, a critical review of some of the relevant literature is included. The near-normal specular reflectance of the (111) face of an orthorhombic sulfur crystal has been measured in both polarized and unpolarized radiation at room temperature. The reflectance of a cryptocrystalline melt freeze has also been obtained. Associated optical constants are determined from a Kramers-Kronig phase shift analysis of the reflectance data. The average reflectance and absolute refractive index n were found to vary with polarization from 0.100 to 0.125 and from 1.92 to 2.09, respectively. Between eight and eleven mostly weak absorption bands of the cyclo-S(8) molecule were discernible, but the attenuation index k remains small throughout most of the region studied. The crystal spectra were found to be quite sensitive to polarization in the neighborhood of the v(4) fundamental. Extrapolation of n to other temperatures and to the liquid phase through the use of the Lorentz-Lorenz relation is discussed.
由于行星天文学的最新进展，人们对元素硫的光学和热力学性质的兴趣再度兴起。预计太空探测器伽利略号与木星卫星，特别是木卫一的交会将进一步激发这种兴趣。本文对正交硫在2至56微米（5000 - 180厘米⁻¹）范围内的光学性质进行了全面研究。鉴于过去对该元素的许多研究不够严谨，本文还对一些相关文献进行了批判性综述。在室温下，测量了正交硫晶体（111）面在偏振和非偏振辐射下的近正入射镜面反射率。还获得了隐晶质熔体凝固物的反射率。通过对反射率数据进行克莱默斯 - 克朗尼格相移分析确定了相关的光学常数。发现平均反射率和绝对折射率n随偏振的变化分别为0.100至0.125和1.92至2.09。在研究的大部分区域中，可分辨出八到十一个主要为弱吸收带的环 - S(8)分子吸收带，但衰减指数k在整个研究区域内仍较小。发现晶体光谱在v(4)基频附近对偏振非常敏感。讨论了通过使用洛伦兹 - 洛伦茨关系将n外推到其他温度和液相的情况。
