Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK.
1] Department of Physics, Imperial College London, Prince Consort Road, London SW7 2AZ, UK [2] Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter EX4 4QL, UK.
Nat Nanotechnol. 2014 Jun;9(6):425-9. doi: 10.1038/nnano.2014.82. Epub 2014 May 4.
Einstein realized that the fluctuations of a Brownian particle can be used to ascertain the properties of its environment. A large number of experiments have since exploited the Brownian motion of colloidal particles for studies of dissipative processes, providing insight into soft matter physics and leading to applications from energy harvesting to medical imaging. Here, we use heated optically levitated nanospheres to investigate the non-equilibrium properties of the gas surrounding them. Analysing the sphere's Brownian motion allows us to determine the temperature of the centre-of-mass motion of the sphere, its surface temperature and the heated gas temperature in two spatial dimensions. We observe asymmetric heating of the sphere and gas, with temperatures reaching the melting point of the material. This method offers opportunities for accurate temperature measurements with spatial resolution on the nanoscale, and provides a means for testing non-equilibrium thermodynamics.
爱因斯坦意识到布朗运动的波动可以用来确定其环境的性质。此后，大量实验利用胶体粒子的布朗运动来研究耗散过程，深入了解软物质物理学，并在从能量收集到医学成像等领域得到应用。在这里，我们使用加热的光学悬浮纳米球来研究它们周围气体的非平衡性质。分析球体的布朗运动可以确定球体质心运动的温度、表面温度以及在两个空间维度中加热气体的温度。我们观察到球体和气体的非对称加热，温度达到材料的熔点。这种方法提供了在纳米尺度上具有空间分辨率的精确温度测量的机会，并为测试非平衡热力学提供了一种手段。
