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<d<5.0 nm) to partially coalesced worm-like island structures (d=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 (k) and refractive index (n) 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 n is increased with the wavelength growth and attains saturation value ns at the wavelength λs. The thicker the films the higher the magnitude of ns and the larger the wavelength λs. Our results of calculations of k(λ) 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 ab initio 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.
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.
Noninvasive monitoring of blood parameters such as total hemoglobin concentration and saturation (oxygenation) is
important for diagnostics in large populations of patients. We developed a novel optoacoustic array for monitoring of
these variables in arteries and veins. The array allows for measurements without scanning, reduces the data acquisition
time, and minimizes the influence of motion artifacts. The array combines a custom-made fiber-optic delivery system
and multiple piezoelectric transducers. We tested the array in vitro and in vivo. The array design and materials allowed
for sensitive measurement of optoacoustic signals without distortion and provided real time measurement of these
parameters both in vitro and in vivo without scanning.