Optical properties of silver nanofilms on its thickness and mechanical deformations in visible and infrared ranges are studied theoretically. The deformation of the film during its elongation leads to a rearrangement of the structure of a surface layer and the appearance of dislocations. It is shown that 9% elongation is crucial for the six monolayer silver film. Mechanical deformations change the electronic structure of atoms in a film, which leads to a significant change in their optical properties. Stretching of the film shifts the absorption peak to the long wavelength region and leads to a slight decrease in absorption. The effects are explained by the significant transformation of the electron structure of deformed silver nanofilms.
Ultrathin (1–10 nm) Cu and Au films were prepared on the silicon and quartz substrates by magnetron sputtering at room temperature. We measured the transmission coefficient of the films at a wavelength of 3cm and analyzed a surface morphology of these films. It was shown that the films with thicknesses less than 7.5 nm (Au) and 3 nm (Cu) are almost transparent for microwaves. This effect is explained by quick oxidation of Cu and the complex surface morphology of nanometer thick films. The Au film morphology is evolved with increasing average Au thickness d from hemispherical islands initially (1.0 nm<<i>d</i><5.0 nm) to partially coalesced worm-like island structures (<i>d</i>=10 nm).
The optical properties of Ag ultrathin films in dependence of their thickness are studied theoretically in a wavelength range 0.3 - 10 μm. The extinction coefficient (<i>k</i>) and refractive index (<i>n</i>) for thin Ag films with smooth surface structure are calculated with software package VASP. It was found the effect of growth of extinction coefficient and shift of its peak into long wavelength range with the thickness increasing. The effect is explained by the significant increasing of the surface electron states. Refractive index <i>n</i> is increased with the wavelength growth and attains saturation value <i>n<sub>s</sub></i> at the wavelength <i>λ<sub>s</sub></i>. The thicker the films the higher the magnitude of <i>n<sub>s</sub></i> and the larger the wavelength <i>λ<sub>s</sub></i>. Our results of calculations of <i>k(λ)</i> are in a good agreement with experimental data from ref.. The difference in magnitudes of n obtained experimentally and theoretically can be explained by the formation of Ag nanoclusters on the surface of sputtered film.
Mechanical properties of freestanding Au-Mn nanowires and Au-Mn nanowire on a Cu (110) substrate are studied with <i>ab initio </i>theoretical approach. The calculations were carried out using the software package Vienna Ab-initio Simulation Package (VASP), which is based on the density functional theory (DFT). It was shown that the breaking force (0.45nN) as well as the interatomic distance at a breaking point in bimetallic nanowire (3.0 Å) are higher than in one component Au wire (0.4 nN and 2.6Å respectively). Relative elongation of 15 % results in a fracture of bimetallic nanowire.<p> </p>We studied the mechanical response of the nanojunction in a form of three-atomic Au chain aligned vertically between two pyramidal gold electrodes and demonstrated that the breaking of nanocontact depends only the interaction between Au atoms in the chain and dependents slightly on the structure and properties of the atomic structure of the electrodes.