分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： The evaporation of water is ubiquitous in nature and industrial technologies. The known mechanism for evaporation is "thermal evaporation" which highlights the energy input for evaporation is via heat. Due to the weak absorption of water to visible light, the first step to using solar energy to evaporate water is usually by converting it into thermal energy through photothermal processes via additional absorbing materials. Contrary to this conventional wisdom, we report here strong absorption of photons in the visible spectrum at the water-vapor interface by direct cleavage of water clusters via a process we call photomolecular effect. We show that this process happens at the water-vapor interface by measuring the dependence of the photomolecular evaporation rate on the wavelength, the angle of incidence, and the polarization of the incident light. The spectra signatures in the vapor phase further support the photomolecular effect. Despite the long propagation lengths of visible light in bulk water, we demonstrate that they can heat a thin layer of fog easily, suggesting that this process is ubiquitous. The photomolecular effect will have significant implications for the earth's water cycle, global warming, plant transpiration, as well as different technologies involving the evaporation of liquids from drying to power generation
分类： 光学 >> 量子光学 提交时间： 2023-02-19
Yuan Zhang
Yuxin Niu
Shunping Zhang
Yao Zhang
Shi-Lei Su
Guangchao Zheng
Luxia Wang
Gang Chen
Hongxing Xu
Chongxin Shan
摘要： Plasmon-mediated superradiance for molecules around metallic nanospheres was proposed ten years ago. However, its demonstration has not been achieved yet due to the experimental difficulty of positioning molecules, and the theoretical limitation to the enhanced collective rate of low excited molecules. In this Letter, we propose that the ultrafast plasmon-mediated superradiant pulses can be observed with strongly excited methylene blue molecules standing vertically inside gold nanoparticle-on-mirror nanocavities. Our simulations indicate that in this system the molecules could interact with each other via plasmon- and free-space mediated coherent and dissipative coupling. More importantly, the coherent coupling mediated by short-ranged propagating surface plasmons cancel largely the direct dipole-dipole coupling mediated by the free-space field, and the dominated dissipative coupling mediated by relatively long-ranged gap plasmons enables the ultrafast superradiant pulses within picosecond scale. Our study opens up the possibility of studying the rich superradiant effects from the quantum emitters in a sub-wavelength volumn by engineering the plasmonic environments.
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