Hoeing Dominik, Salzwedel Robert, Worbs Lena, Zhuang Yulong, Samanta Amit K, Lübke Jannik, Estillore Armando D, Dlugolecki Karol, Passow Christopher, Erk Benjamin, Ekanayake Nagitha, Ramm Daniel, Correa Jonathan, Papadopoulou Christina C, Noor Atia Tul, Schulz Florian, Selig Malte, Knorr Andreas, Ayyer Kartik, Küpper Jochen, Lange Holger
The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Hamburg 22761, Germany.
Department of Chemistry, Universität Hamburg, Hamburg 20146, Germany.
Nano Lett. 2023 Jul 12;23(13):5943-5950. doi: 10.1021/acs.nanolett.3c00920. Epub 2023 Jun 23.
Dynamics of optically excited plasmonic nanoparticles are presently understood as a series of scattering events involving the initiation of nanoparticle breathing oscillations. According to established models, these are caused by statistical heat transfer from thermalized electrons to the lattice. An additional contribution by hot-electron pressure accounts for phase mismatches between theory and experimental observations. However, direct experimental studies resolving the breathing-oscillation excitation are still missing. We used optical transient-absorption spectroscopy and time-resolved single-particle X-ray diffractive imaging to access the electron system and lattice. The time-resolved single-particle imaging data provided structural information directly on the onset of the breathing oscillation and confirmed the need for an additional excitation mechanism for thermal expansion. We developed a new model that reproduces all of our experimental observations. We identified optically induced electron density gradients as the initial driving source.
目前，光激发等离子体纳米颗粒的动力学被理解为一系列散射事件，其中涉及纳米颗粒呼吸振荡的启动。根据已建立的模型，这些是由热化电子向晶格的统计热传递引起的。热电子压力的额外贡献解释了理论与实验观察之间的相位失配。然而，仍缺少解决呼吸振荡激发的直接实验研究。我们使用光学瞬态吸收光谱和时间分辨单粒子X射线衍射成像来研究电子系统和晶格。时间分辨单粒子成像数据直接提供了呼吸振荡开始时的结构信息，并证实了热膨胀需要额外的激发机制。我们开发了一个新模型，该模型再现了我们所有的实验观察结果。我们确定光诱导电子密度梯度为初始驱动源。
