Role of coherence in the plasmonic control of molecular absorption

Abstract

The interpretation of nanoplasmonic effects on molecular properties, such as metal-enhanced absorption or fluorescence, typically assumes a fully coherent picture (in the quantum-mechanical sense) of the phenomena. Yet, there may be conditions where the coherent picture breaks down, and decoherence effect should be accounted for. Using a state-of-the-art multiscale model approach able to include environment-induced dephasing, here we show that metal nanoparticle effects on the light absorption by a nearby molecule is strongly affected (even qualitatively, i.e., suppression vs enhancement) by molecular electronic decoherence. The present work shows that decoherence can be thought as a further design element of molecular nanoplasmonic systems.

LayerPCM: An implicit scheme for dielectric screening from layered substrates

“…This is an interference effect between the oscillating dipoles due to the incident and reflected fields, which have some arbitrary phase relationship. 101 At the minimum around 18 fs, the induced dipole moment of the system is reduced to almost zero, while part of the excited-state population is retained. Afterwards, the dipole moment is built back up by absorption.…”

Investigating ultrafast two-pulse experiments on single DNQDI fluorophores: a stochastic quantum approach

“…1): (i) description of the electronic structure of the spectroscopic target by means of DFT/TDDFT; (ii) electronic properties (excitation energies and transition dipole moments) are then ''dressed'' by a proper vibrational structure, using the quantities computed at step (i); (iii) a realtime propagation of the vibronic wave packet is performed, in terms of close (''standard'' time-dependent Schrödinger equation) and open quantum (SSE) systems, using the quantities from steps (i) and (ii) as input parameters. 43,44 Using DFT/ TDDFT to characterize states for many-electron dynamics has been performed before. 24,25,47 In this section, we briefly review the SSE protocol and the methodology to vibrationally dress the electronic states.…”

“…In the model developed before 43 relaxation has been included via radiative (spontaneous) emission and nonradiative decay processes. According to previous studies, 43,44,48,56 relaxation has been included by the operator…”

“…The fluorophore time propagation is computed through the stochastic Schrödinger equation (SSE) [40][41][42] within the Markovian limit. 43,44 In this model, dissipation and fluctuations due to the environment are included by means of stochastic terms in every realization of the wave function evolution. Averaging over a number of realizations leads to results equivalent to the Lindblad master equation solution with the advantage of less computational effort.…”

Strong Coupling between Localized Surface Plasmons and Molecules by Coupled Cluster Theory

“…Strong coupling between molecules and quantum plasmons in nanocavities leads to the formation of hybrid plasmon–molecule states: polaritons, or more specifically, plexcitons . These new states manifest distinct features compared to the original states, − potentially resulting in modified chemical/photochemical reactivity − and relaxation dynamics, , along with other coherent processes. , Modeling accurately the molecules, nanostructures and their coupling is of the utmost importance to support the experimental advances. Coupling descriptions proper for resonant optical cavities, such as using the molecular dipole only, , should be amended − when the coupling affects the molecule on a submolecular level. ,, …”