Optical Properties of Cu2O Thin Films Impregnated with Carbon Nanotube (CNT)

This study investigates CNT-doped Cu2O thin film deposited by spray pyrolysis technique at a substrate temperature of 100°C. The samples were annealed at temperatures of 200°C and 230°C for 30 minutes. The effect of CNT doping on certain optical properties, such as extinction and absorption coefficients, a refractive index of doped Cu2O thin films were examined. The absorbance of the doped samples increases within the visible range and decreases in the ultraviolet range of the electromagnetic spectrum (EM). Both absorbance and extinction coefficients increased with temperature making the samples a good candidate for use as absorbance layer in device fabrication. In addition, there was an increase in direct bandgap with the increase in CNT concentration of the thin films. The result of the study revealed that CNT doping has a significant effect on the properties of Cu2O.

Wakefield Formation by a Short Electron Beam in Quantum Nanowires

The basic properties of classical and quantum plasmas are discussed. Quantum plasmas behave differently due to high densities and low temperatures at nanometer scale in contrast to classical ones which are characterized by low densities and high temperatures. A literature survey is made to investigate the plasma phenomenon with quantum mechanical effects. Classical and quantum viewpoints are also presented to understand the free electron gas in metals. In particular, the excitation of stable plasmon wakefield is studied due to a short electron pulse propagating in axial direction of nanowire. The latter contains degenerate electrons and classical static ions. By using the Trivelpiece-Gould configuration and Fourier transform techniques, a general dispersion is obtained for the electrostatic plasmons and analyzed numerically. Nevertheless, an evolution equation for the wakefield is derived and carried out the stability analysis. In a gold nanowire, the amplitudes of wakefield become significantly modified by the variation of quantum diffraction, quantum exchange-correlations and mode quantization in the radial direction. The present findings may prove useful for investigating new radiation sources in the extreme-ultraviolet range.

The Interaction of the 2D MoP2 and NbP2 Surfaces with Carbon Dioxide and Carbon Monoxide and Changes in Their Optical Properties

Using first-principles molecular dynamics (FPMD) simulations at atmospheric pressure and 300 K, we investigated the adsorption of the molecules CO and CO2 on each of the surfaces of the 2D materials MoP2 and NbP2. We found that both surfaces adsorbed the carbon monoxide molecule but not the carbon dioxide. The adsorption energy on the MoP2 surface was −0.9398 eV, and on the NbP2 surface, −0.9017 eV. Furthermore, we obtained substantial changes in the optical properties of each 2D material after the CO adsorption. For the two materials, the optical absorption shows significant changes in the ultraviolet region. Furthermore, the two surfaces present essential changes in the ultraviolet range in the case of reflectivity.

Influence of Growth Conditions on Mechanical Properties of K2NiXCo(1−X) (SO4)2·6H2O Crystals

K2NiXCo(1−X) (SO4)2·6H2O (KCNSH) mixed crystal is a promising material for solar blind optical filters, combining high transparency in the ultraviolet range with effective suppression of the visible spectral region. Increasing the mechanical strength of these crystals is important to enable them to be machined in the manufacture of optical elements. A comprehensive study of the inhomogeneities and crack resistance of KCNSH crystal as a function of the growth conditions was carried out. The influence of the radial and mosaic inhomogeneity, as well as other structural defects, on the crack resistance of the crystals was analyzed. To assess the crack resistance of crystals, the parameters ca (crack length), c/a (the ratio of crack length to the size of the indentation), and KC (fracture toughness) were used. The correctness of the obtained results was analyzed. The conditions for growing KCNSH crystals with the best crack resistance were determined on the basis of the results of the study. It is shown that growing the mixed crystals using the temperature difference technique with a peripheral solution supply into the shaper provides the best crystal quality.

Total column ozone measurements by the Dobson spectrophotometer at Belsk (Poland) for the period 1963–2019: homogenization and adjustment to the Brewer spectrophotometer

The total column ozone (TCO3) measurements by the Dobson spectrophotometer (serial no. 84) have been carried out at Belsk station (51∘50′ N, 20∘47′ E), Poland, since 23 March 1963. In total, ∼115 000 intraday manual observations were made by 31 December 2019. These observations were performed for different combinations of double wavelength pairs in the ultraviolet range and observation types, i.e., direct sun (DS), zenith blue (ZB), and zenith cloudy (ZC) depending on weather conditions. The long-term stability of the instrument was supported by frequent (almost every 4 years) intercomparisons with the world standard spectrophotometer. Trend analyses, based on the monthly and yearly averaged TCO3, can be carried out without any additional corrections to the intraday values. To adjust these data to the Brewer spectrophotometer observations, which were also performed at Belsk, a procedure is proposed to account for less accurate Dobson observations under low solar elevation, presence of clouds, and the temperature dependence of ozone absorption. The adjusted time series shows that the Brewer–Dobson monthly averaged differences are in the range of about ±0.5 %. The intraday TCO3 database, divided into three periods (1963–1979, 1980–1999, and 2000–2019), is freely available at https://doi.org/10.1594/PANGAEA.919378 (Rajewska-Więch et al., 2020).

First-Principles Investigation of structural, Optical, and Electrical properties of MgO Nanocrystals

Nanocrystal interfaces can strongly influence the optical and electrical properties and charging trapping phenomena observed on oxide nanocrystal ensembles. The well-defined shape and controllable size distributions of MgO nanocrystals are a convenient system for studying these effects. Therefore, in the present work focused on the effect of temperature on the optical and electrical properties of magnesium oxide (MgO) nanocrystals, together with the responsible atomic centers, the bulk MgO is a study based on the first principle functional density theory (DFT) using PBE-GGA approximations. The absorption coefficient shows that MgO shows good coverage in the ultraviolet range. The bulk MgO is a direct bandgap nanocrystal at G point in the Brillion Zone despite the temperature applied values. The temperature is applied to alter the bandgap pattern and closes the bandgap at a high temperature. The PDOS and imaginary part of the dielectric function further confirm the insulator properties of the observed bandgap. Our results show that the optical properties are affected by the inconsistent temperature manners despite the different temperatures given to the system. Our absorption curve confirms that the nanocrystal is a good candidate for ultraviolet device application with a significantly high reflectivity percentage.

Analog Spatial Light Modulators Based on Micromirror Arrays

The Fraunhofer Institute for Photonic Microsystems (IPMS) has been developing and manufacturing micromirror arrays for more than 20 years. While originally focusing on applications related to microlithography and therefore mainly for light in the deep ultraviolet range, the range of applications has been expanded since, including applications in the visible and near-infrared range. This paper gives an overview of the devices and their designs, fabrication, and characterization.