Molekularions

Molekularions are a theoretical class of quasi-particles proposed in models of charge transport within molecular systems. They are described as emergent excitations that combine a localized charge with a coherent lattice or intramolecular vibrational distortion, forming a bound state that behaves as a single, mobile entity.

Origin and formation: Molekularions arise when a charge carrier in a molecular lattice interacts strongly with vibrational degrees of freedom. The coupling traps part of the lattice distortion around the carrier, creating a stable, dressed state. This concept is related to polaron physics but emphasizes an ionic character and pronounced coupling to molecular-scale vibrations.

Properties and dynamics: A molekularion is predicted to carry a net electric charge, while its motion is governed by both electronic and vibrational dynamics. Its effective mass is enhanced relative to a free electron by the accompanying lattice distortion. The dispersion and mobility of molekularions depend on molecular geometry, coupling strength, temperature, and the spectrum of vibrational modes present in the material.

Experimental status: Evidence for molekularions remains indirect and theoretical. Some studies report spectroscopic features in infrared or terahertz ranges that could reflect charge-lattice coupled states, and time-resolved measurements may hint at coupled charge-phonon dynamics. However, unambiguous identification is lacking, and the concept remains a topic of ongoing debate and investigation.

Potential significance: If experimentally confirmed, molekularions could influence charge transport in organic semiconductors, molecular electronics, and energy transfer processes. They would offer a framework for understanding transport that intertwines electronic motion with specific vibrational modes, guiding design strategies for materials with tailored conductivity and excitations.