Infrared optical properties of thin H 2 O, NH 3 , and CO 2 cryofilms
Infrared optical properties of thin H 2 O, NH 3 , and CO 2 cryofilms
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H 2 O、NH 3 和 CO 2 冷冻膜的红外光学特性
DOI：
10.1364/josa.72.000720
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发表时间：
1982
影响因子：
--
通讯作者：
J. Roux
中科院分区：
文献类型：
--
作者：
B. Wood;J. Roux
为了确定和占从低温污染的影响，由CO2，H2O，和NH3形成的cryofilms的红外光谱透射率进行了测量。这些0.25-14 μ m厚的薄膜被低温泵送到20-、80-和在一种情况下50-K的锗衬底上;在20 K下沉积的薄膜和80-K薄膜的沉积压力约为2 × 10 - 6 Torr。用傅里叶变换光谱仪获得500-3700-cm-1范围的透射光谱。CO2，H2O，和NH3 cryofilms的光学性质（n，k）的值来自使用薄膜透射率分析模型和非线性最小二乘法的实验数据。将最小二乘法的结果与Kramers-Kronig测定的折射率（n）进行比较。这种低温薄膜的光学性质（n，k）是必不可少的预测污染的低温冷却光学表面的退化。
To identify and account for the effects from cryocontamination, the infrared spectral transmittances of cryofilms formed by CO2, H2O, and NH3 were measured. These 0.25–14-μm-thick films were cryopumped onto 20-, 80-, and in one case 50-K germanium substrates; the deposition pressures for the films deposited at 20 K and that for 80-K films were approximately 2 × 10−6 Torr. Transmittance spectra were obtained for the 500–3700-cm−1 range with a Fourier-transform spectrometer. Values of the optical properties (n, k) for the CO2, H2O, and NH3 cryofilms were derived from the experimental data using a thin-film-transmittance analytical model and the nonlinear least-squares method. Results from the least-squares method are compared with a Kramers–Kronig determination of the refractive index (n). The optical properties (n, k) of such cryofilms are essential for predicting the degradation of contaminated cryocooled optical surfaces.