Experimental and Ab Initio Ultrafast Carrier Dynamics in Plasmonic Nanoparticles
Experimental and Ab Initio Ultrafast Carrier Dynamics in Plasmonic Nanoparticles
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DOI：
10.1103/physrevlett.118.087401
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发表时间：
2017-02-21
影响因子：
8.6
通讯作者：
Atwater, Harry A.
中科院分区：
文献类型：
--
作者：
Brown, Ana M.;Sundararaman, Ravishankar;Atwater, Harry A.
等离子体纳米结构的超快泵浦探针测量探测了受激载流子的非平衡行为，其中涉及典型经验分析中掩盖的几种竞争效应。在这里，我们提出了等离子体纳米粒子的泵浦探针测量以及基于载流子动力学和光学响应的第一原理计算的完整理论描述，没有任何拟合参数。我们考虑了态密度、激发载流子分布、电子声子耦合和介电函数等详细的电子结构效应，这些效应使我们能够避免有效的电子温度近似。使用这种计算方法，我们在瞬态吸收测量中获得了与光谱和时间特征良好的定量一致性。在我们的实验和计算中，我们确定了具有不同特征的初始响应的两个主要贡献：短寿命的高度非热激发载流子和寿命较长的热化载流子。
Ultrafast pump-probe measurements of plasmonic nanostructures probe the nonequilibrium behavior of excited carriers, which involves several competing effects obscured in typical empirical analyses. Here we present pump-probe measurements of plasmonic nanoparticles along with a complete theoretical description based on first-principles calculations of carrier dynamics and optical response, free of any fitting parameters. We account for detailed electronic-structure effects in the density of states, excited carrier distributions, electron-phonon coupling, and dielectric functions that allow us to avoid effective electron temperature approximations. Using this calculation method, we obtain excellent quantitative agreement with spectral and temporal features in transient-absorption measurements. In both our experiments and calculations, we identify the two major contributions of the initial response with distinct signatures: short-lived highly nonthermal excited carriers and longer-lived thermalizing carriers.