Optical trapping and Raman spectroscopy of solid particles.
Optical trapping and Raman spectroscopy of solid particles.
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DOI：
10.1039/c4cp00994k
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发表时间：
2014-05
期刊：
影响因子：
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通讯作者：
L. Rkiouak;Mingjin Tang;Mingjin Tang;J. Camp;James McGregor;I. M. Watson;R. Anthony Cox;Markus Kalberer;Andrew D. Ward;F. D. Pope
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文献类型：
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作者：
L. Rkiouak;Mingjin Tang;Mingjin Tang;J. Camp;James McGregor;I. M. Watson;R. Anthony Cox;Markus Kalberer;Andrew D. Ward;F. D. Pope
气体分子与固体颗粒之间的非均匀相互作用在科学、工程和技术的许多领域都是至关重要的。这种相互作用在大气化学和多相催化中发挥着关键作用，多相催化是能源和化学工业的关键技术。研究单个悬浮粒子上的异质相互作用可以为这些重要过程提供重要的见解。存在用于悬浮微米尺寸颗粒的各种方法，包括：光学、电学和声学技术。在这项研究之前，固体微米级颗粒的光学悬浮已被证明难以在与上述应用相关的时间尺度上实现。在这项工作中，一个新的垂直配置的反向传播双光束光学陷阱进行了优化，悬浮在空气中的固体颗粒的范围。二氧化硅（SiO2）、α-氧化铝（Al 2 O3）、二氧化钛（TiO 2）和聚苯乙烯被稳定地捕获，具有高捕获效率（Q = 0.42）。最长稳定诱捕实验连续进行24小时，超过此时间对诱捕时间没有明显限制。因此，本文所描述的方法应该是各种研究团体的主要利益。通过拉曼光谱法对二氧化硅颗粒的同时悬浮和光谱询问，证明了新技术的强度。特别地，在受控的相对湿度环境下研究了水在二氧化硅上的吸附。此外，使用光学成像和拉曼光谱学，二氧化硅颗粒与硫酸微滴的碰撞和凝聚行为。
The heterogeneous interactions of gas molecules on solid particles are crucial in many areas of science, engineering and technology. Such interactions play a critical role in atmospheric chemistry and in heterogeneous catalysis, a key technology in the energy and chemical industries. Investigating heterogeneous interactions upon single levitated particles can provide significant insight into these important processes. Various methodologies exist for levitating micron sized particles including: optical, electrical and acoustic techniques. Prior to this study, the optical levitation of solid micron scale particles has proved difficult to achieve over timescales relevant to the above applications. In this work, a new vertically configured counter propagating dual beam optical trap was optimized to levitate a range of solid particles in air. Silica (SiO2), α-alumina (Al2O3), titania (TiO2) and polystyrene were stably trapped with a high trapping efficiency (Q = 0.42). The longest stable trapping experiment was conducted continuously for 24 hours, and there are no obvious constraints on trapping time beyond this period. Therefore, the methodology described in this paper should be of major benefit to various research communities. The strength of the new technique is demonstrated by the simultaneous levitation and spectroscopic interrogation of silica particles by Raman spectroscopy. In particular, the adsorption of water upon silica was investigated under controlled relative humidity environments. Furthermore, the collision and coagulation behaviour of silica particles with microdroplets of sulphuric acid was followed using both optical imaging and Raman spectroscopy.