Theoretical Investigation of Electron and Nuclear Dynamics in the [Au₂₅(SH)₁₈]⁻¹ Thiolate-Protected Gold Nanocluster

Abstract

Clear mechanistic insights into excited state dynamics in thiolate-protected gold nanoclusters are vital for understanding the origin of the photocatalytic enhancement via metal nanoparticles in the visible region. Extensive experimental studies on the [Au25(SR)18]−1 thiolate-protected gold nanocluster nonradiative relaxation dynamics reported very distinct time constants which span from the femtosecond to nanosecond scale. In this work, the nonradiative excited state relaxations of the [Au25(SH)18]−1 cluster are investigated theoretically to characterize the electron relaxation dynamics. The core and higher excited states lying in the energy range 0.00–2.20 eV are investigated using time-dependent density functional theory (TD-DFT). The quantum dynamics of these states is studied using a surface hopping method with decoherence correction, augmented with a real-time approach to DFT. Population transfer from the S1 state to the ground state occurs on the several hundred picoseconds time scale. Relaxation between excited states that arise from core-to-core transitions is found to occur on a much shorter time scale (2–18 ps). No semiring or other states are observed at an energy lower than the core-based S1 state. This observation suggests that the several picosecond time constants observed by Moran and co-workers could arise from core-to-core transitions rather than from a core-to-semiring transition. A large energy gap between the S7 and S6 states is found to be responsible for a relatively slow decay time for S7. The S1 state population decrease demonstrates the slowest decay time due to the large energy gap to the ground state. The spectral densities are calculated to understand the electron–phonon interactions that lead to electronic relaxations.

Charge transfer dynamics at the boron subphthalocyanine chloride/C60 interface: non-adiabatic dynamics study with Libra-X

“…At the same time, as our practice suggests, the transitions between rigorously-defined multi-electronic states are often dominated by the transitions between the frontier orbitals. 85 Thus, the use of the 1-electron orbitals provides a practical way for obtaining qualitative and semi-quantitative insights into the charge and energy transfer dynamics in extended systems. Finally, one of the goals of the present work is to assess the potential differences in NA dynamics that may originate in the level of electronic structure treatment, nuclear dynamics, and intermolecular interactions used, as well as the NA-MD algorithm used.…”

Bonding of Two 8‐Electron Superatom Clusters

“…Clusters such as sodium (Na n ), aluminum (Al n ), gold (Au n ), and alloy clusters, with certain numbers of atoms have been discovered to exhibit pronounced intensities in their mass spectra. Among these, the “magic‐sized” clusters with analogous valence electron configuration to atomic electron structure are regarded as superatoms, and a closed‐shell electronic configuration for such clusters in a sphere model has been developed for understanding their extraordinary stability . Further, several experimental and theoretical studies present that the superatom clusters can serve as the building block to form assemblies or compounds in combination with other atoms or superatom .…”

A superatomic molecule under the spin‐orbit coupling: Insights from the electronic properties in the thiolate‐protected Au38(SR)24 cluster

“…A particularly interesting class of gold nanoparticles is displayed by thiolate protected (–SR) structures, where great advances have been achieved over the last two decades. In this concern, structural and optical properties has been well explored, reflecting the inherent relationship between geometric and electronic structure. Au 25 (SR) 18 and Au 38 (SR) 25 are two prototypical examples for thiolate protected clusters, which can be considered as a central core embedded in a structural protecting layer .…”