Anisotropic Polarizability-Induced Plasmon Transfer

Despite the large number of technological applications relying on noble metal nanoparticles' collective electron oscillations, or localized surface plasmon resonances (LSPR), a complete understanding of all factors affecting their dynamics has not yet been achieved. In this paper, a nonadiabatic Ehrenfest dynamics approach is employed to investigate the dynamics of a linear chain of silver atoms initialized in the transverse LSPR state. Out-of-chain motions are shown to cause the increase of one specific off-diagonal component of the molecular polarizability, inducing a polarization orthogonal to the direction of the transverse LSPR oscillation and consistent with the molecule's geometrical orientation. These geometry changes allow the transfer from the initially excited transverse plasmon to a multipolar longitudinal plasmon. This unique plasmon transfer mechanism, allowed only by the symmetry change of the system and never observed before, sheds light on a previously unknown feature of metal nanoparticles.