Department of Chemical Engineering, University of Florida, Gainesville, FL 32611, USA.
J Colloid Interface Sci. 2012 Mar 15;370(1):11-8. doi: 10.1016/j.jcis.2011.12.058. Epub 2012 Jan 2.
Here we report the sensitive and reversible detection of vapors by using self-assembled colloidal photonic crystals. The condensation of various vapors in the interstitials of silica colloidal photonic crystals leads to red-shift and amplitude reduction of optical stop bands. A linear relationship between wavelength shift and vapor partial pressure has been observed for a variety of vapors including ethanol, water, and toluene. Importantly, the sensitivity of colloidal photonic crystal-based vapor detectors can be improved by nearly two orders of magnitude by using a new full-peak analysis technique that takes advantage of the manifest amplitude reduction of optical stop bands during vapor condensation. Optical simulation based on a scalar-wave approximation model shows that the predicted optical responses during vapor condensation in colloidal photonic crystals agree well with experimental results. The condensation of vapors between submicrometer-scale microspheres, a topic that has received little examination, has also been investigated by both experiments and theoretical calculations. Predictions based on a modified Kelvin equation match with the experiments for a wide range of vapor partial pressures.
在这里，我们报告了使用自组装胶体光子晶体对蒸气进行灵敏和可逆检测。各种蒸气在二氧化硅胶体光子晶体的间隙中的冷凝导致光带隙的红移和幅度减小。对于包括乙醇、水和甲苯在内的多种蒸气，已经观察到波长移动与蒸气分压之间的线性关系。重要的是，通过利用蒸气冷凝过程中光带隙明显减小的全新全峰分析技术，基于胶体光子晶体的蒸气探测器的灵敏度可以提高近两个数量级。基于标量波近似模型的光学模拟表明，胶体光子晶体中蒸气冷凝期间预测的光学响应与实验结果吻合良好。蒸气在亚微米级微球之间的冷凝是一个研究较少的课题，也通过实验和理论计算进行了研究。基于修正的 Kelvin 方程的预测与宽蒸气分压范围内的实验结果相匹配。
