Understanding electron transport in self-assembled monolayers on metal nanoparticles (NPs) is crucial for developing NP-based nanodevices. This study investigates ultrafast electron transport through aromatic molecules on NP surfaces via resonant Auger electron spectroscopy (RAES) with a core-hole-clock (CHC) approach. Aromatic molecule-coated Au NPs are deposited to form condensed NP films, and flat monolayers are prepared for comparison. Soft X-ray techniques, including X-ray photoelectron spectroscopy and near-edge X-ray absorption fine structure spectroscopy, confirm oriented monolayers in both NP and flat films. The nuclear dynamics is studied via ion yield measurements. After subtracting secondary processes, the ion yield spectra of the condensed NP films reveal site-selective desorption of the methyl ester group by resonant core excitation. The ultrafast electron transport time from the carbonyl group through the phenyl rings to the metal surfaces in the condensed NP films is successfully determined via the RAES-CHC approach by subtracting inelastic scattering components. The chain length of the aromatic molecules influence the electron transport time in the NP films, reflecting the trends observed in the flat films. This evidence supports ultrafast electron transport via the through-bond model, independent of interactions between the molecules adsorbed on an NP itself or adjacent NPs. Identifying and subtracting background spectral components of the condensed NP films allows accurate analysis of the ultrafast dynamics. This study suggests that insights gained from electron transport processes in the flat monolayer films can be extrapolated to practical NP–molecule interfaces, providing valuable insights for the molecular design of NP-based devices.

中文翻译：

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金纳米颗粒上芳香族分子电子传输的比较研究：凝聚纳米颗粒薄膜与平面单层薄膜的软 X 射线光谱的见解


了解金属纳米颗粒 （NP） 上自组装单层中的电子传输对于开发基于 NP 的纳米器件至关重要。本研究通过采用核-空穴-时钟 （CHC） 方法的共振俄歇电子谱 （RAES） 研究了 NP 表面通过芳香族分子的超快电子传输。沉积芳香族分子包被的 Au NPs 以形成冷凝的 NP 膜，并制备平坦的单层以进行比较。软 X 射线技术，包括 X 射线光电子能谱和近边缘 X 射线吸收精细结构光谱，可确认 NP 和平面薄膜中的定向单层。通过离子产额测量研究核动力学。减去二次过程后，浓缩 NP 膜的离子产率谱揭示了通过共振核激发对甲酯基团的位点选择性解吸。通过 RAES-CHC 方法减去非弹性散射分量，成功确定了从羰基通过苯环到凝聚 NP 薄膜中金属表面的超快电子传输时间。芳香族分子的链长会影响 NP 薄膜中的电子传输时间，反映了在平面薄膜中观察到的趋势。该证据支持通过通键模型进行超快电子传输，与吸附在 NP 本身或相邻 NP 上的分子之间的相互作用无关。识别和减去凝聚 NP 膜的背景光谱分量可以准确分析超快动力学。 这项研究表明，从平面单层膜中的电子传输过程中获得的见解可以外推到实际的 NP 分子界面，为基于 NP 的器件的分子设计提供有价值的见解。