Plasmon Decay Pathways in Magic-Sized Nanoclusters: Hot-Carrier Dynamics for Photocatalyst Design

Abstract Effective use of plasmonic materials in photocatalysis requires not only generation of hot electrons but also understanding their energy distribution and active sites across the surface of the nanocluster. In this work, we investigated the relaxation pathways for plasmons via electron–electron scattering, the prominent plasmon damping mode among nanoclusters. Utilizing a novel methodology based on the use of TDDFT eigenstates as well as molecular orbital (MO) eigenstates to represent the density matrix, we found distinct plasmon decay behavior in the magic-sized clustersAl13−1 and Au13+5, due to their electronic structures. For Al13−1, this includes broadening of the hot-electron energy distribution, valence electron impact excitation, and coupled upconversion–downconversion which leads to hot carriers with energy up to 2hν followed by decay that includes interband MO (sp→d) transitions.Au13+5 shows more typical behavior, with strong participation of d-orbital hole formation, and no contribution from coupled upconversion-downconversion, highlighting the impact of the constituent metal. Exploration of the electron density evolution during plasmon decay revealed the primary density maxima in Al13−1to be at the opposing vertices of the icosahedron that are aligned with the applied field. This analysis provides the spatial and energetic distributions of the hot electrons, information that is essential for designing ligands for efficient plasmonic photocatalysis.