Advances of the Holographic Technique to Test the Basic Properties of the Thin-Film Organics: Refractivity Change and Novel Mechanism of the Nonlinear Attenuation Prediction

Abstract

A large number of the thin-film organic structures (polyimides, 2-cyclooctylarnino-5-nitropyridine, N-(4-nitrophenyl)-(L)-prolinol, 2-(n-Prolinol)-5-nitropyridine) sensitized with the different types of the nano-objects (fullerenes, carbon nanotubes, quantum dots, shungites, reduced graphene oxides) are presented, which are studied using the holographic technique under the Raman-Nath diffraction conditions. Pulsed laser irradiation testing of these materials predicts a dramatic increase of the laser-induced refractive index, which is in several orders of the magnitude greater compared to pure materials. The estimated nonlinear refraction coefficients and the cubic nonlinearities for the materials studied are close to or larger than those known for volumetric inorganic crystals. The role of the intermolecular charge transfer complex formation is considered as the essential in the refractivity increase in nano-objects-doped organics. As a new idea, the shift of charge from the intramolecular donor fragment to the intermolecular acceptors can be proposed as the development of Janus particles. The energy losses via diffraction are considered as an additional mechanism to explain the nonlinear attenuation of the laser beam.

Keywords: COANP; NPP; PNP; carbon nanoparticles and tubes; intermolecular charge transfer complex formation; laser-matter interaction; organic structures; polyimides; refractivity change.

Figure 1

The proposed extended scheme of intermolecular charge transfer using organic conjugated materials, where the introduced intermolecular doping nano-object has an electron affinity significantly greater than the intramolecular acceptor of the matrix system.