Двумерные кулоновские плазмон-экситоны: релаксация возбуждений

A theory is developed for the relaxation of two-dimensional non-radiative (Coulomb) plasmon-excitons in thin closely located layers of a metal and a semiconductor. In the framework of classical electrodynamics, the equations of motion are formulated for the polarization waves of non-radiative plasmons and excitons with taking into account the Coulomb coupling and the near-field of external polarization. In the model of coupled harmonic oscillators represented by the polarization fields of excitations, the problem of relaxation is solved for Coulomb plasmons, excitons and plasmon-excitons. It is shown that the two dispersion branches of normal plasmon-exciton modes undergo anticrossing (mutual repulsion) at the resonance between plasmon and exciton. With dissipative damping and power interchange between the excitations taken into account, the process of plasmon-exciton relaxation depending on time is investigated. The theory displays the principal analogies between dynamics of plasmon-excitons and of excitations in other objects of linear vibration theory, such as mechanical oscillators, resonant electric chains, etc.

Intersubband Optical Nonlinearity of GeSn Quantum Dots under Vertical Electric Field

The impact of vertical electrical field on the electron related linear and 3rd order nonlinear optical properties are evaluated numerically for pyramidal GeSn quantum dots with different sizes. The electric field induced electron confining potential profile’s modification is found to alter the transition energies and the transition dipole moment, particularly for larger dot sizes. These variations strongly influence the intersubband photoabsorption coefficients and changes in the refractive index with an increasing tendency of the 3rd order nonlinear component with increasing both quantum dot (QD) size and applied electric field. The results show that intersubband optical properties of GeSn quantum dots can be successively tuned by external polarization.

Composite La0.6Sr0.4Co0.8Fe0.2O3/Ag Cathode For SoFCs With Ce0.8Sm0.2O1.9 Electrolyte / Kompozytowa Katoda La0.6Sr0.4Co0.8Fe0.2O3/Ag Do Stało-Tlenkowych Ogniw Paliwowych Z Elektrolitem Ce0.8Sm0.2O1.9

Influence of the short time external polarization of silver electrode contacted Ce0.8Sm0.2O1.9 electrolyte was studied. Silver is moving along the Ce0.8Sm0.2O1.9 surface during the -0.5 V cathodic polarization at 600°C. It caused both the increase of the electrode - electrolyte contact area and the triple phase boundary length but also decrease of electrolyte and polarization resistances. Deposit of silver oxide was found at the place where the electrode polarized at the potential of 0.5 V contacted the electrolyte and around. The decrease of electrolyte and polarization resistance was smaller but more stable in this case. Composite cathodes were obtained on Ce0.8Sm0.2O1.9 electrolyte with the double step sintering procedure. Silver introduced into a La0.6Sr0.4Co0.8Fe0.2O3 cathode improved a performance of a La0.6Sr0:4Co0.8Fe0.2O3|Ce0.8Sm0.2O1.9|Ni cell by 33%.