University of Illinois Urbana-Champaign

Mapping Electronic Relaxation Dynamics In Metal Nanoclusters Using Polarization-selective Two-dimensional Electronic Spectroscopy

Jeffries, William R.

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WD01_1.pptx
6106.pdf

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https://hdl.handle.net/2142/116602

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Title
Mapping Electronic Relaxation Dynamics In Metal Nanoclusters Using Polarization-selective Two-dimensional Electronic Spectroscopy
Author(s)
Jeffries, William R.
Contributor(s)
Knappenberger, Jr., Kenneth L.
Issue Date
2022-06-22
Keyword(s)
Clusters/Complexes
Abstract
Gold monolayer protected clusters (MPCs) are a class of quantum-confined metal nanostructures that span the transition from molecular to metallic electron dynamics. MPCs are well-described by three structural motifs that include (i) an all-metal atom core, (ii) an inorganic semiring of alternating Au-S staple units, and (iii) passivating organic ligands. The structure and composition of these domains influence the nanocluster optical and electronic properties, providing a well-defined platform to elucidate structure-dependent energy relaxation mechanisms in quantum confined metals. In this presentation, ultrafast electronic and charge carrier relaxation will be discussed. Coherent two-dimensional electronic spectroscopy (2DES) provides an excitation-detection frequency-frequency correlation by spreading the transient signal over two axes that spectrally and temporally resolves state-to-state electron dynamics on the femtosecond timescale. Here, 2DES was used to distinguish several electronic fine-structure peaks that comprise a charge transfer resonance in molecular-like Au$_{38}$(SC$_{6}$H$_{13}$)$_{24}$ nanoclusters. By manipulating the polarization vector of the femtosecond pulses, additional insights on the coupling of transition dipole moments were obtained from cross-peak specific spectra. These results revealed a low-amplitude excited state absorption signal that uniquely relaxed through a charge transfer resonance within 150 femtoseconds. Evidence of population changes of excited vibrational states within the electronic manifold, which undergo intramolecular vibrational relaxation (IVR), were quantified by fitting time-dependent amplitudes of 2DES-detected cross-peaks spanning a frequency range of 1000 cm$^{-1}$. Anisotropy and orientation parameters obtained from polarization-selective 2DES were applied to better understand state-specific relaxation through coupled electronic states. Solvent dependences on charge carrier relaxation will be discussed. These results demonstrate the ability of polarization-selective 2DES to map state-resolved electron dynamics in molecular-like metal nanoclusters.
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
eng
Handle URL
https://hdl.handle.net/2142/116602
DOI
https://doi.org/10.15278/isms.2022.WD01
Copyright and License Information
Copyright 2022 held by the authors

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Abstracts & Presentations - 2022 International Symposium on Molecular Spectroscopy PRIMARY