Polaritonic Chemistry with Organic Molecules

Abstract

Esta es la versión de autor del artículo publicado en: This is an author produced version of a paper published in:El acceso a la versión del editor puede requerir la suscripción del recurso Access to the published version may require subscription AbstractWe present an overview of the general concepts of polaritonic chemistry with organic molecules, i.e., the manipulation of chemical structure that can be achieved through strong coupling between confined light modes and organic molecules. Strong coupling and the associated formation of polaritons, hybrid light-matter excitations, leads to energy shifts in such systems that can amount to a large fraction of the uncoupled transition energy. This has recently been shown to significantly alter the chemical structure of the coupled molecules, which opens the possibility to manipulate and control reactions. We discuss the current state of theory for describing these changes and present several applications, with a particular focus on the collective effects observed when many molecules are involved in strong coupling.Keywords polaritonic chemistry, photochemistry, organic molecules, quantum optics 1 When the coherent energy exchange between a confined light mode and a quantum emitter becomes faster than the decay and decoherence of either constituent, the system enters into the regime of strong coupling or vacuum Rabi splitting. 1,2 The fundamental excitations of the system are then polaritons, hybrid light-matter excitations. This requires a large (collective)where N is the number of involved emitters, µ is their transition dipole moment, and E 1ph ∝ V −1/2 is the electric field strength associated with one photon in the light mode (with V its effective mode volume). The figure of merit for a material is thus its dipole density µ 2 N/V , with organic materials presenting a particularly favorable case due to their large dipole moments and high possible density. In addition, the large binding energies of Frenkel excitons in organic materials make them stable at room-temperature. This has allowed reaching the strong-coupling regime with a large variety of electromagnetic (EM) modes, 3 such as cavity photons, 4-8 surface plasmon polaritons, [9][10][11][12] surface lattice resonances, 13,14 and localized surface plasmons. 15,16 Typical Rabi frequencies range from ≈ 100 meV to more than 1 eV, a significant fraction of the uncoupled transition energy, for a wide range of organic materials such as dye molecules, J-aggregates, and even carbon nanotubes. 17,18 By using localized surface plasmon modes with extreme-subwavelength light confinement, recent experiments have achieved strong coupling at room temperature even down to the single-emitter level. [19][20][21] The mixed light-matter character of organic polaritons enables a large number of interesting applications (see Ref. 22 for a recent review discussing polaritonic devices, including a comparison between organic and inorganic materials), such as polariton lasing and/or Bose-Einstein condensation 23-25 including nonlinear ...

Three-player polaritons: nonadiabatic fingerprints in an entangled atom–molecule–photon system

“…The splitting of the atomic peak at 14 800 cm −1 in the middle right panel of figure 1 as well as the appearance of purple colored peaks near 15 100 cm −1 indicates that a considerable mixing of the atomic and molecular states occurred. Increasing the atom number to N a while keeping the cavity field strength fixed leads to (1) an √ N a times increased effective atom-cavity coupling, resulting in a shift in the atomic transition frequency, (2) an N a times increased atomic line strengths, and (3) the appearance of N a − 1 dark states, see lower left panel of figure 1. Our numerical results show, as expected, that these dark states have no significant contribution to the spectrum (see lower right panel of figure 1).…”

Polaritonic normal modes in transition state theory

“…Also, the effect on the kinetics has been observed to increase as the collective coupling intensifies, as a consequence of the large number of molecules present in a sample. 1 These observations are reminiscent of the description of light-matter coupling in terms of hybrid states known as polaritons, [7][8][9][10][11][12] which successfully explains the optical properties of these systems. [13][14][15][16][17] Recently, it has been suggested that a class of nonadiabatic charge transfer reactions would experience a catalytic effect from resonant collective coupling between high-frequency modes and infrared cavity modes; the mechanism relies on the formation of vibrational polaritons which feature reduced activation energies compared to the bare molecules.…”

Strong Coupling with Light Enhances the Photoisomerization Quantum Yield of Azobenzene

“…The high flexibility of the polaritonic properties has been assessed for both realized 20,24,25 and potential applications 13,26 giving birth to a new branch of chemistry 27 : the so-called polaritonic chemistry. 28 When a resonant mode is coupled to electronic transitions, the molecules exhibit enhanced spontaneous emission at both the collective and single molecule level [29][30][31][32] .…”