Nonradiative Energy Losses of Plasmon-Polariton in a Metallic Nano-chain Deposited on a Semiconductor Substrate

2023

Preprint

Ion plasmon-polariton model of stimulus in myelinated axons and in C fibers of pain sensation is developed. This solves a long standing problem in neuroscience of by 2 − 3 orders of magnitude discrepancy between the observed fast speed of the saltatory conduction in myelinated axons or in C fibers with the upper limit of diffusive ion current velocity in these axons. The latter, described in the framework of so-called cable model, is too low in axons because of poor conductivity of neuron inner cytosol. The compliance with observations has been achieved upon plasmonic model of ionic local oscillations synchronized in periodically corrugated axons and propagating with high speed in the form of wave-type plasmon-polariton without any net diffusion current, thus not limited by resistivity. The new model of stimulus in myelinated axons reveals the different controlling role of myelin than previously thought from cable model. The control mechanism in non-myelinated C fibers is also proposed in agreement with observations. Recognition of plasmon model of neural signaling may be important for identifying a new targets for the future treatment at demyelination diseases and for fighting pain.

Section: Fitting the Plasmon-polariton Kinetics To The Myelinated Axo...supporting

confidence: 54%

Explanation of saltatory conduction in myelinated axons and of micro-saltatory conduction in C fibers of pain sensation by a wave-type ion plasmonic mechanism of stimulus kinetics

2023

Preprint

“…This large effect causes the reducing of the frequency, according to the damped oscillator scheme, , where is the overall damping rate for plasmons in a single chain element. This damping causes a similar increase of damping of the plasmon-polariton (Jacak 2019 ). Inclusion of this damping and related of the plasmon self-frequency gives the frequency of the order of MHz for a realistic diameter of the axon, m.…”

Section: Plasmon-polariton Model Of Saltatory Conduction: Fitting Thementioning

confidence: 90%

New wave-type mechanism of saltatory conduction in myelinated axons and micro-saltatory conduction in C fibres

2020

Eur Biophys J

We present a new wave-type model of saltatory conduction in myelinated axons. Poor conductivity in the neuron cytosol limits electrical current signal velocity according to cable theory, to 1-3 m/s, whereas saltatory conduction occurs with a velocity of 100-300 m/s. We propose a wave-type mechanism for saltatory conduction in the form of the kinetics of an ionic plasmon-polariton being the hybrid of the electromagnetic wave and of the synchronized ionic plasma oscillations in myelinated segments along an axon. The model agrees with observations and allows for description of the regulatory role of myelin. It explains also the mechanism of conduction deficiency in demyelination syndromes such as multiple sclerosis. The recently observed micro-saltatory conduction in ultrathin unmyelinated C fibers with periodic ion gate clusters is also explained.

“…Note, however, that the property ( 26) is out of reach for numerical simulations with predefined dielectric functions with optical constants from bulk, as it requires the inclusion of large plasmon damping due to the Lorentz friction in all nano-segments of the chain (taken into account in ( 25) by first terms in the imaginary parts for both polarisations). If, however, the metallic nano-chain is embedded in or deposited on some absorbing medium (like a semiconductor substrate), then the coupling of plasmons in spheres of the chain in the near-field zone to the band electrons in the absorbing nearby-located system causes energy transfer (possible to be accounted for by Fermi golden rule), which increases plasmon-polariton non-radiative damping [32].…”

Section: A B C Dmentioning

confidence: 99%

On Damping of Plasmons and Plasmon-Polaritons in Metallic Nanostructures and Its Influence onto Numerical Simulations

Krzemińska

2023

Plasmonics

Self Cite

We show that the damping of plasmons in metallic nanoparticles highly exceeds that caused by scattering of electrons on defects, phonons, and other electrons and on boundaries of particles. The radiation losses in far-field zone due to the Lorentz friction is especially high at nanometre scale of metal confinement (e.g. attains the maximum at ca. 100 nm diameter of particle, Au in vacuum). This causes a different e-m response of such size structures in comparison to conventional solution of Maxwell-Fresnel equations using the bulk dielectric function for metal. The strong discrepancy occurs also if plasmons are coupled in near-field zone to nearby-located absorbing medium, e.g. semiconductor substrate. This coupling cannot be accounted for by classical electrodynamic treatment (e.g. by numerical solution of Maxwell equations by finite element method for differential equation solution) and needs the application of quantum Fermi golden rule to estimate plasmon damping and related modifications of dielectric functions both of metallic nanoparticles and of absorbing medium. Similarly, the perfect cancellation of radiative losses of plasmon-polaritons in metallic nano-chains is beyond classical Maxwell equation modelling, as it reveals the perfect vanishing of Lorentz friction losses in chain segments by radiative contribution from other segments in near-, medium- and far-field zones. This demonstrates that nano-plasmonic effects cannot be reliably numerically modelled using material parameters from conventional packets referred to optical constants measured in bulk.