High optical absorptivity or a large absorption cross-section is necessary to fully utilize the irradiation of light for photothermal heating. Recently, titanium nitride (TiN) nanostructures have been demonstrated to be robust optical absorbers in the optical range owing to their nonradiative decay processes enhanced by broad plasmon resonances. Because the photothermally generated heat dissipates to the surroundings, suppressing heat transfer from TiN nanostructures is crucial for maximizing the photothermal temperature increase. In the current work, compared to the planar TiN film, high-aspect-ratio TiN nanostructures with subwavelength periodicities have been demonstrated to enhance the photothermal temperature increase by a 100-fold using nanotube samples. The reason is attributed to the extremely anisotropic effective thermal conductivities. Our work has revealed that high-aspect-ratio TiN nanostructures are effective in improving photothermal heating, and they can be used in various applications, such as solar heating, chemical reactions, and microfluidics.

中文翻译：

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高纵横比氮化钛纳米结构中的极端热各向异性，可实现有效的光热加热

为了充分利用光的照射来进行光热加热，需要高的光学吸收率或大的吸收截面。最近，由于氮化钛（TiN）纳米结构的非辐射衰减过程被宽等离振子共振增强，因此在光学范围内已被证明是坚固的光学吸收体。由于光热产生的热量会散发到周围，因此抑制TiN纳米结构的热传递对于最大限度地提高光热温度至关重要。在目前的工作中，与平面TiN膜相比，具有纳米波长周期性的高纵横比TiN纳米结构已被证明可以使用纳米管样品将光热温度升高100倍。原因归因于极各向异性的有效热导率。