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The structural and optical investigation of thin films containing aluminum and gallium phthalocyanine chlorides is presented. The films were fabricated by Physical Vapor Deposition technique onto quartz substrates and annealed after fabrication in an ambient atmosphere for 24 h at the temperature equal to 150 °C or 250 °C. The experimental results and theoretical calculation of the Third Harmonic Generation process are reported. The third order nonlinear optical properties are expected and can be more or less accurately predicted due to the assembly of the molecules and theoretical calculations of the frequency-dependent dipole polarizabilities, third hyperpolarizabilities, third order susceptibilities, frontier and second frontier molecular orbitals. These parameters were used to understand the relationship of optical properties with the molecular structures. We found that the annealing process causes formation of nanostructures and the value of the third order optical susceptibility makes these materials interesting for future nonlinear optical applications.

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Wetting is very common phenomenon, and it is well documented that the wettability of a solid depends on the surface density of adsorbed airborne hydrocarbons. This “hydrocarbon hypothesis” has been experimentally confirmed for different surfaces, for example, graphene, TiO2, and SiO2; however, there are no scientific reports describing the influence of airborne contaminants on the water contact angle (WCA) value measured on the polytetrafluoroethylene (PTFE) surface. Using experimental data showing the influence of airborne hydrocarbons on the wettability of graphene, gold and PTFE by water, together with Molecular Dynamics simulation results we prove that the relation between the WCA and the surface concentration of hydrocarbons (n-decane, n-tridecane, and n-tetracosane) is more complex than has been assumed up until now. We show, in contrast to commonly approved opinion, that adsorbed hydrocarbons can increase (graphene, Au) or decrease (PTFE) the WCA of a nanodroplet sitting on a surface. Using classical thermodynamics, a simple theoretical approach is developed. It is based on two adsorbed hydrocarbon states, namely, “carpet” and “dimple”. In the “carpet” state a uniform layer of alkane molecules covers the entire substrate. In contrast, in the “dimple” state, the preadsorbed layer of alkane molecules covers only the open surface. Simple thermodynamic balance between the two states explains observed experimental and simulation results, forming a good starting point for future studies.

In this paper, we present the third harmonic generation response of Znq2 (Bis-(8-hydroxyquinolinato)zinc), Cuq2 (8-Hydroxyquinoline copper(II)), and Alq3 (Tris-(8-hydroxyquinoline)aluminum) organometallic compounds. An experiment was conducted for s and p polarizations of incident beam, using the Maker fringes technique. The third order nonlinear susceptibility χ(3) was estimated using the Kubodera and Kobayashi comparative model, on the grounds that presented compounds exhibit high linear absorption of the generated third harmonic wavelength (355 nm). These complexes were deposited as thin films using the physical vapor deposition (PVD) method. Investigated complexes vary in terms of the coordination center and number of quinoline ligands, which visibly influence their nonlinear response. The global hybrid B3LYP functional with the basis set 6-31G(d) was used in computing the linear and non-linear optical properties. The computed γtot value (8765.36 × 10−36 esu for Cuq2) is superior to that of methylene blue (γ = 32.00 × 10−36 esu). The calculated theoretical values were found to be in good agreement with the experimental results.