Work

Effects of Electronic Structure on Molecular Plasmon Dynamics

Year: 2020

Type: article

Abstract: Collective, coherent excitations in molecules, termed molecular plasmons, can be observed in neutral and charged polycyclic aromatic hydrocarbons (PAHs). Systems in this few-atom limit show behavior strongly dependent on charge state, where the addition or removal of even a single electron dramatically alters electronic and optical properties. Here, we investigate the dynamics of PAHs by studying their excited-state lifetimes in four different charge states: cation, neutral, anion, and dianion. Those characterized by a closed-shell electronic structure—the neutral molecule and the dianion—exhibit long-lived, exponentially decaying lifetimes typical of radiative relaxation. In contrast, the open-shell cationic and anionic states exhibit far more rapid multiexponential decay dynamics. This can be attributed to the nonradiative de-excitation of multiple electron–hole pairs in the molecule through molecular plasmon “dephasing” and vibrational relaxation. This study gives insight into the nature of excited states of open- and closed-shell molecules and illuminates the role played by electronic structure in the collective electron dynamics of few-atom plasmonic systems.

Source: The Journal of Physical Chemistry C

DOI: 10.1021/acs.jpcc.0c06072