Selective Absorption in Twolayered Optic Films

Abstract

This paper summarizes theoretical investigations of changes in optical properties of smallest symmetrical nanofilm-molecular crystals due to the presence of boundaries and different boundary parameters. Using analytic and numerical calculations, the energy spectrum of excitons was found and relative permittivity of these ultrathin dielectric films was determined. The influence of boundary parameters on the occurrence of discrete (by parameters) and selective (by planes) absorption of external electromagnetic radiation was also investigated. Because of the symmetric conditions on film boundaries, double resonant peaks appear.

Consequences of Confinement Conditions on Absorption in Molecular Nanofilms

“…In order to find a spectrum of exciton energies, we need poles of the Green functions, which are obtained when a determinant of a system (3.2) is identically equalized to zero [12][13][14]…”

“…Calculation of roots, i.e. poles of the Green functions, due to impossibility of finding analytic solution (except in an ideal film case [12][13][14]), was found numerically and presented graphically (see Appendix A). The calculations are, due to the inability to find general analytical solutions, made with the help of adequate software (which we developed ourselves; see Appendix B for corresponding code lines).…”

“…Analyses were done using the innovated method of Green functions, adapted for investigation of quantum structures [10][11][12][13][14]. Due to adequately incorporated statistics, this method is successfully applied in calculating both microscopic and macroscopic, balanced and imbalanced, properties of crystals.…”

Successive absorption and refraction of ultrathin molecular nano-films

“…Uzimajući u obzir granične uslove (3) i izraze za hamiltonijan (1) i jednačinu kretanja (2) dolazimo do jednačine za tražene Grinove funkcije [11][12][13][14][15]. Nakon potpune vremenske, ali sada i samo delimične prostorne Furije-transformacije ovih jednačina, dobijamo:…”

“…Kako su nam za nalaženje zakona disperzije potrebni samo polovi ovih funkcija, dovoljno je naći determinantu sistema (4) i istu izjednačiti sa nulom [11][12][13][14][15]. Na ovaj način dobijamo N+1 rešenje…”