Precise control and measurement of solid-liquid interfacial temperature and viscosity using dual-beam femtosecond optical tweezers in the condensed phase.
Precise control and measurement of solid-liquid interfacial temperature and viscosity using dual-beam femtosecond optical tweezers in the condensed phase.
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DOI：
10.1039/c6cp03093a
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发表时间：
2016-09
期刊：
影响因子：
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通讯作者：
Dipankar Mondal;Paresh Mathur;D. Goswami
中科院分区：
文献类型：
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作者：
Dipankar Mondal;Paresh Mathur;D. Goswami
我们提出了一种新的基于飞秒光钳的微观流变学方法，它使我们能够直接测量和控制固-液界面上微尺度体积的原位温度。非侵入性的780 nm脉冲捕获微珠由于溶剂分子和捕获微珠之间的相互能量传递而自发地响应于同向传输的1560 nm脉冲激光引起的环境变化。1560 nm激光对羟基的强烈吸收在水和醇的单独和二元混合物中产生局部加热。捕获的聚苯乙烯微珠的“热布朗运动”反映在由功率谱推导出的拐角频率上。拐角频率值的变化使我们能够计算固-液界面的粘度和温度。我们表明，这些实验结果也可以在理论上得到证实。
We present a novel method of microrheology based on femtosecond optical tweezers, which in turn enables us to directly measure and control in situ temperature at microscale volumes at the solid-liquid interface. A noninvasive pulsed 780 nm trapped bead spontaneously responds to changes in its environment induced by a co-propagating 1560 nm pulsed laser due to mutual energy transfer between the solvent molecules and the trapped bead. Strong absorption of the hydroxyl group by the 1560 nm laser creates local heating in individual and binary mixtures of water and alcohols. "Hot Brownian motion" of the trapped polystyrene bead is reflected in the corner frequency deduced from the power spectrum. Changes in corner frequency values enable us to calculate the viscosity as well as temperature at the solid-liquid interface. We show that these experimental results can also be theoretically ratified.