Superatom State-Resolved Dynamics of the Au25(SC8H9)18‿/sup> Cluster from Two-Dimensional Electronic Spectroscopy

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• 作者：Tatjana Stoll ; Enrico Sgrò ; Jeremy W. Jarrett ; Julien Réhault ; Aurelio Oriana ; Luca Sala ; Federico Branchi ; Giulio Cerullo ; Kenneth L. Knappenberger Jr.
• 刊名：Journal of the American Chemical Society
• 出版年：2016
• 出版时间：February 17, 2016
• 年：2016
• 卷：138
• 期：6
• 页码：1788-1791
• 全文大小：342K
• ISSN：1520-5126

文摘

Superatom state-resolved dynamics of the Au₂₅(SC₈H₉)₁₈^– monolayer-protected cluster (MPC) were examined using femtosecond two-dimensional electronic spectroscopy (2DES). The electronic ground state of the Au₂₅(SC₈H₉)₁₈^– MPC is described by an eight-electron P-like superatom orbital. Hot electron relaxation (200 ± 15 fs) within the superatom D manifold of lowest-unoccupied molecular orbitals was resolved from hot hole relaxation (290 ± 20 fs) in the superatom P states by using 2DES in a partially collinear pump–probe geometry. Electronic relaxation dynamics mediated by specific superatom states were distinguished by examining the time-dependent cross-peak amplitudes for specific excitation and detection photon energy combinations. Quantification of the time-dependent amplitudes and energy positions of cross peaks in the 2.21/1.85 eV (excitation/detection) region confirmed that an apparent energetic blue shift observed for transient bleach signals results from rapid hot electron relaxation in the superatom D states. The combination of structurally precise MPCs and state-resolved 2DES can be used to examine directly the influence of nanoscale structural modifications on electronic carrier dynamics, which are critical for developing nanocluster-based photonic devices.