Plasmons and Plasmon–Polaritons in Finite Ionic Systems: Toward Soft-Plasmonics of Confined Electrolyte Structures

Abstract

We address the field of soft plasmonics in finite electrolyte liquid systems ranged by insulating membranes by an analogy to the plasmonics of metallic nanostructures. The confined electrolyte systems can be encountered on a bio-cell organizational level, taking into account that the characteristics of ion plasmons fall to the micrometer size scale instead of the nanometer in metals because of at least three orders of magnitude larger masses of ions in comparison to electrons. The lower density of ions in electrolytes in comparison to density of electrons in metal may also reduce the energy of plasmons by several orders. We provide the fully analytical description of surface and volume plasmons in finite ionic micro-systems allowing for further applications. We next apply the theory of ionic plasmons to plasmon–polaritons in ionic periodic systems. The complete theory of ionic plasmon–polariton kinetics in the chain of micrometer-sized electrolyte spheres, confined by a dielectric membrane, is formulated and solved. The latter theory has next been applied to the explanation of a mysterious and unclear (for several dozen of years) problem of so-called saltatory conduction of the action potential in myelinated axons of nerve cells. Contrary to conventional models of nerve signaling, the plasmon–polariton model pretty well fits to the queer properties of the saltatory conduction. Moreover, the presented application of soft plasmonics to signaling in periodically myelinated axons may allow for identification of a different role in information processing of the white and gray matters in brain and spinal cord. We have outlined some perspectives to utilize the difference between the electricity of myelinated and non-myelinated nerve cells in brain to develop the topological concept of the memory functioning. The proposed ionic plasmon–polariton model of the saltatory conduction differently recognizes the role of the insulating myelin than previously was thought which may be helpful in the development of a better understanding of the demyelination diseases.

Nonlocal Soft Plasmonics in Planar Homogeneous Multilayers

“…Ionic plasmon-polaritons have been investigated for spherical electrolytes, embedded, e.g., in an insulating membrane and chains thereof. Such models provide an alternative description of saltatory conduction observed in nerve cells [42]. In addition, loss mechanisms beyond classical electrodynamics such as size-dependent plasmon damping, ohmic-type energy dissipation, and radiative losses were discussed [43,44].…”

Radioplasmonics: design of plasmonic milli-particles in air and absorbing media for antenna communication and human-body in-vivo applications.

“…A novel Plasmonic concept is shown in macroscale with particle dimensions less than a few millimeters or centimeters [48], where it would be easy to carry out experiments to study complex plasmonic phenomena as, for instance, multiple particle coupling [21]. This work naturally includes previous efforts to define plasmonics in extremely low-energies [27,[48][49][50][51][52]. The latest ideas about SPs are simplified since "bulk" materials with simple geometries are used here.…”

Nonlocal and Size-Dependent Dielectric Function for Plasmonic Nanoparticles

“…Classical local electrodynamics in nanostructures under the assumption that the polarization characteristics at a given point are locally related to the external electromagnetic excitation, which has been thoroughly explored from isolated nanoparticles and dimers to other complex structures [1][2][3][4][5]. On the other hand, the nonlocal response of a metal nanostructure to an external disturbance stimulus determines many important plasmonic properties and has attracted much theoretical interest [6][7][8][9].…”