Zhu Dezhi, Yan Jianfeng, Xie Jiawang
Opt Lett. 2020 Apr 1;45(7):1758-1761. doi: 10.1364/OL.384326.
Gold nanorod (Au NR) is an attractive material due to its superior physical and chemical properties. Various applications in diagnostics and biomedicine have been demonstrated. The single-pulse laser is commonly used to reshape nanoparticles in a solvent; however, the laser-material reaction mechanisms underlying nanoparticle reshaping remain unclear. Here, we report the reshaping of Au NRs by ultrafast pump-probe-like double-pulse laser irradiation to understand the reaction dynamics. We demonstrate the enhancement of double-pulse-induced reshaping, which provides an opportunity to design new Au NR structures. It shows that the reshaping enhancement is dependent on the delay time (${\tau _s}$τ) between a pair of separated pulses. The absorption peak wavelength of Au NRs exposed to the shaped double pulse was lower than that of using a single pulse of the same total fluence when ${\tau _s}$τ was less than the electron-phonon relaxation time. This phenomenon was mainly attributed to changes in electronic heat transport and electron-phonon coupling, which affected the pulse delay-dependent nanorod (NR) temperature.
金纳米棒（Au NR）因其优异的物理和化学性质而成为一种有吸引力的材料。它已在诊断和生物医学领域展现出各种应用。单脉冲激光通常用于在溶剂中重塑纳米颗粒；然而，纳米颗粒重塑背后的激光 - 材料反应机制仍不清楚。在此，我们报告通过超快泵浦 - 探测式双脉冲激光辐照对金纳米棒进行重塑，以了解反应动力学。我们展示了双脉冲诱导重塑的增强，这为设计新的金纳米棒结构提供了机会。结果表明，重塑增强取决于一对分离脉冲之间的延迟时间（${\tau _s}$）。当${\tau _s}$小于电子 - 声子弛豫时间时，暴露于成形双脉冲的金纳米棒的吸收峰波长低于使用相同总能量密度的单个脉冲时的吸收峰波长。这种现象主要归因于电子热传输和电子 - 声子耦合的变化，这影响了与脉冲延迟相关的纳米棒（NR）温度。
