Jeffries William R, Park Kyoungweon, Vaia Richard A, Knappenberger Kenneth L
Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, United States.
Air Force Research Laboratory, 2941 Hobson Way, Wright-Patterson Air Force Base, Ohio 45433, United States.
Nano Lett. 2020 Oct 14;20(10):7722-7727. doi: 10.1021/acs.nanolett.0c03272. Epub 2020 Sep 29.
The use of two-dimensional electronic spectroscopy (2DES) to study electron-electron scattering dynamics in plasmonic gold nanorods is described. The 2DES resolved the time-dependent plasmon homogeneous line width Γ(), which was sensitive to changes in Fermi-level carrier densities. This approach was effective because electronic excitation accelerated plasmon dephasing, which broadened Γ. Analysis of Γ() indicated plasmon coherence times were decreased by 20-50%, depending on excitation conditions. Electron-electron scattering rates of approximately 0.01 fs were obtained by fitting the time-dependent Γ broadening; rates increased quadratically with both excitation pulse energy and frequency. This rate dependence agreed with Fermi-liquid theory-based predictions. Hot electron thermalization through electron-phonon scattering resulted in Γ narrowing. To our knowledge, this is the first use of the plasmon Γ() to isolate electron-electron scattering dynamics in colloidal metal nanoparticles. These results illustrate the effectiveness of 2DES for studying hot electron dynamics of solution-phase plasmonic ensembles.
描述了使用二维电子光谱（2DES）研究等离子体金纳米棒中的电子-电子散射动力学。2DES解析了随时间变化的等离子体均匀线宽Γ()，其对费米能级载流子密度的变化敏感。这种方法是有效的，因为电子激发加速了等离子体退相，从而拓宽了Γ。对Γ()的分析表明，根据激发条件，等离子体相干时间减少了20-50%。通过拟合随时间变化的Γ展宽获得了约0.01 fs的电子-电子散射速率；速率随激发脉冲能量和频率呈二次方增加。这种速率依赖性与基于费米液体理论的预测一致。通过电子-声子散射实现的热电子热化导致Γ变窄。据我们所知，这是首次使用等离子体Γ()来分离胶体金属纳米颗粒中的电子-电子散射动力学。这些结果说明了2DES在研究溶液相等离子体集合体的热电子动力学方面的有效性。
