Diroll Benjamin T, Jeong Soojin, Ye Xingchen
Center for Nanoscale Materials Argonne National Laboratory 9700 S. Cass Avenue Lemont IL 60439 USA.
Department of Chemistry Indiana University 800 E. Kirkwood Avenue Bloomington IN 47405 USA.
Small Sci. 2021 Dec 15;2(3):2100103. doi: 10.1002/smsc.202100103. eCollection 2022 Mar.
Colloidal copper nanorods (NRs) display transverse and longitudinal localized surface plasmon resonances. The longitudinal localized surface plasmon modes are tunable through the near-infrared electromagnetic radiation energies with NR aspect ratios. Visible and near-infrared transient optical response of the copper NRs is investigated under excitation conditions spanning intraband and interband excitation (0.79-3.50 eV). In both the visible and near-infrared regions, the spectral response of the samples under intraband excitation (<2 eV) differs substantially from their response under interband excitation (>2 eV). However, the timescale of the electron-phonon coupling estimated from pump fluence-dependent measurements ( ) is less sensitive to excitation conditions than reports for gold. shortens slightly from ≈616 fs with intraband excitation (at visible probe energies) to ≈565 fs with interband excitation. The observed dynamics correspond to an average sample electron-phonon coupling parameter varying across all conditions from 4.4 × 10 to 6.4 × 10 J m K, which is similar to bulk copper. Furthermore, coherent acoustic phonons are observed for the longitudinal localized surface plasmon resonance with a range of oscillatory periods reflecting sample size dispersion.
胶体铜纳米棒（NRs）表现出横向和纵向的局域表面等离子体共振。纵向局域表面等离子体模式可通过具有纳米棒纵横比的近红外电磁辐射能量进行调谐。在跨越带内和带间激发（0.79 - 3.50 eV）的激发条件下，研究了铜纳米棒的可见和近红外瞬态光学响应。在可见和近红外区域，带内激发（<2 eV）下样品的光谱响应与带间激发（>2 eV）下的响应有很大不同。然而，从依赖泵浦能量密度的测量中估计的电子 - 声子耦合时间尺度（ ）对激发条件的敏感度低于金的相关报道。 从带内激发（在可见探测能量下）时的约616 fs略微缩短至带间激发时的约565 fs。观察到的动力学对应于在所有条件下变化的平均样品电子 - 声子耦合参数，范围为4.4×10 至6.4×10 J m K，这与块状铜相似。此外，对于纵向局域表面等离子体共振观察到了相干声子，其具有一系列反映样品尺寸分散的振荡周期。
