Dragana Rodić

Consequences of Confinement Conditions on Absorption in Molecular Nanofilms

Consequences of Confinement Conditions on Absorption in Molecular Nanofilms I.J. Šetrajčića,∗, D. Rodić, J.P. Šetrajčić, A.J. Šetrajčić-Tomić, S.M. Vučenović University of Novi Sad, Faculty of Sciences, Department of Physics, 21000 Novi Sad, Vojvodina, Serbia University of Novi Sad, Faculty of Medicine, Department of Pharmacy, 21000 Novi Sad, Vojvodina, Serbia University of Banja Luka, Faculty of Sciences — Physics, 78000 Banja Luka, Republic of Srpska — B&H

Discretization of optical properties in symmetrical nanofilm-structures

Based on microscopic (exciton) theory of optical properties of symmetrically perturbed ultrathin molecular films, the absorption, reflection and transparency indices were formulated and presented in the function of frequencies of external electromagnetic field in near infrared (IR) region. It has been showed that all optical properties depend on the position of the crystal plane with regard on boundary planes of the film. We have determined and analyzed optical properties relations for the whole film structure based on the consideration for multiple reflection, absorption and transparency in those multilayered structure. The three-layered dielectric nanofilms with different boundary conditions on surfaces were analyzed and some discrete resonant absorption lines were obtained. Their number, position and distribution depend on the boundary parameter values, i.e. on the type and the technological process of their preparation/fabrication. Practically monochromatic absorption may occur. Unlike the corresponding bulk-samples which are total absorbers throughout the near IR region, in ultrathin films will appear selective and discrete reflection and transparency too. These results could give a great contribution in optical engineering of nanostructures, especially in technology of designing of new electronic and photonic equipment, and for nanoparticles construction for drug carrier/delivery in nano-medicine.

Influence of symmetric perturbations on optical properties of molecular nanofilms

In this paper we have calculated optical changes under the influence of the boundary conditions in molecular crystalline nanostructured films. We have used theoretical model with the adjusted Greens functions, and using numerical calculations we have calculated dispersion law for excitons, and their spatial distribution along the boundary planes. In this procedure we limited ourselves on case with symmetrically perturbed conditions, and showed that the primary optical properties significantly change just in these planes where perturbations have main influence. We have determined coefficient of absorption, reflection, transparency and refraction on the base of real and imaginary part of the relative dielectric permittivity. Especially interesting case is that those structures show significantly contribution of the reflective and transparent radiation in the IR part of the spectra, while the same material in bulk almost completely absorb radiation in this part of spectra.

Changes in optical characteristics of dielectric nanofilm structures in relation to bulk ones

A microscopic theory of optical properties of ideal ultrathin molecular films, was formulated in bosonic and nearest-neighbor approximation. Calculating of dynamical permittivity by the single-pole Greens functions have shown that the threshold of light absorption, refraction, reflection and transmission can be moved along frequencies, changing the film thickness. This can give a great contribution to practical ultrathin film engineering, especially to construction of drug delivery nanoparticles in nanomedicine.