Modulating Molecular Plasmons in Naphthalene via Intermolecular Interactions and Strong Light-Matter Coupling

Abstract

We conduct a theoretical investigation on the modulation of plasmon-like resonances of the naphthalene molecule — the so-called molecular plasmons — through intermolecular interactions and strong light-matter coupling. The configuration interaction with single excitations (CIS) approach and its quantum electrodynamics extension (QED-CIS-1) are used to describe the molecular plasmon state under these interactions. We detail the effects of controlling intermolecular distance of the naphthalene dimer and incorporating the naphthalene molecule into optical cavities, both allowing for precise control of naphthalene's plasmonic responses. Our results show significant shifts of the plasmon peak in the absorption spectra of naphthalene, dependent on spatial configuration of the dimer and cavity parameters such as polarization, frequency, and coupling strength. This research provides insights into the plasmonic behavior of simple polyacenes like naphthalene and opens up possibilities for the plasmon modulation in more complex systems.