Optical constants of nanofilms of J aggregates of organic dyes, measured by spectral ellipsometry and polarization reflectometry

The dispersion of the complex refractive index of thin films of J aggregates of organic dyes has been measured by spectral ellipsometry and polarization reflectometry. It is found that almost all films of J aggregates exhibit normal dispersion in the long-wavelength region, where the films are transparent. In the spectral range where the films absorb, anomalous dispersion is observed with a maximum in the J peak. The refractive index n in this range becomes as high as ?2.5–3.5. It is revealed that polarization reflectometry provides adequate accuracy in determining the optical constants n and κ of nanofilms of organic dyes.     

Optical hyperlens composed of multilayered metallodielectric nanofilms

We present a study of the properties of metamaterial consisting of multilayered nanofilms and numerically demonstrate the subwavelength imaging effect. We find that a point source placed in the vicinity of the structure can form an image in the opposite side of the slab, even when the permittivity of metal and dielectric materials is not matched. When light is incident obliquely on the interface, the intensity of transmitted field is smaller than the one when light is incident upon the structure, and the image becomes blurred. This structure verifies that the multilayered metallodielectric structure can act as optical hyperlens.     

Optical constants of thin germanium films

The paper gives the values of the optical constants of thin films of germanium obtained by evaporating germanium in a vacuum onto glass slides in the region of 0·35–0·78 for an index of absorptionk and 0·35–2·5 for refractive indexn. The results are compared with the values obtained by other authors and with the values ofn andk for single crystals. It is shown that these values for thin films and single crystals slightly differ quantitatively but agree fairly well qualitatively, which had not been sufficiently the case in previous papers.

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, , 0,35 0,78 k 0,35–2,5 n. n, k . , , , , .

     

Optical constants of single crystal GaAs

The optical constants of single crystal GaAs were determined in the range 0.6 to 4.2 eV, using Tomlin’s method and are compared in the light of the earlier results obtained using the Kramers-Krönig analysis method.     

Optical constants of substances of atmospheric aerosol

The optical constants of the chemical compounds constituting the atmospheric aerosol were investigated in a wide spectral range. This investigation indicates that higher values of the refractive index than that of water must be used in calculations of the optical characteristics of the aerosol in the IR region. The main absorption bands of the aerosol in the atmospheric windows are determined.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 91–97, May, 1972.     

Solid-phase synthesis of solid solutions in Cu/Ni(001) epitaxial nanofilms

Solid-phase synthesis of solid solutions in the epitaxial Cu/Ni(001) bilayer film systems of compositions 3Cu: 1Ni, 1Cu: 1Ni, and 1Cu: 3Ni has been studied using the X-ray diffraction methods. The saturation magnetization and the magnetic crystallographic anisotropy constant on nickel vary in accordance with the solid solution formation. The initiation temperature of the solid solutions is about 350 °C and is independent of the Ni: Cu layer thickness ratio. The solid-phase synthesis of the solid solutions is presumably attributed to the transport of the Cu atoms to the epitaxial Ni(001) layer. It is found that the solid-phase synthesis in the Cu/Ni bilayer nanofilms and multilayers is determined by the spinodal decomposition in the Cu-Ni system.     

Optical constants of nanosized films of metal titanium

A new ellipsometric technique for optical measurements of the refraction and extinction indices and thickness of nanosized metal-titanium films in air is proposed and implemented. It is shown that the determination of optical constants of titanium films by measuring the ellipsometric parameters Ψ and Δ for a light beam incident upon the metal/substrate interface through the substrate of fused silica allows one to obtain optical constants of the metal, which correlate well with the results of the most reliable measurements performed in vacuum chambers. In this case, one can additionally determine the thickness and refractive index of the natural oxide film on the titanium surface. The obtained values of the optical constants of titanium, n ₂ = 3.42 ± 0.05 and k ₂ = 3.75 ± 0.05 (λ = 632.8 nm), agree well with the results of the measurements made in vacuum. The proposed technique makes it possible to measure the thicknesses of titanium films within the range 7–30 nm with an accuracy of 0.7 nm. The technique is tested on titanium films deposited onto fused silica substrates obtained by vacuum thermal evaporation. The possible error of determining the thickness due to various additional factors is estimated. The results of ellipsometric measurements of the thickness are compared with the data obtained from parallel measurements of electric resistance of the films.     

Optical constants of titanium and silicon dioxide films

In this paper a study of optical constants of titanium and silicon dioxide films prepared in Balzers BAK 600 and BA 510 conventional high-vacuum apparatus is described. Both the dispersion and the geometrical thickness were determined from normal reflectance spectrum by adapted general algorithm of the statistical interpretation of measured data. The dependence of optical constants on oxygen pressure for both materials and the evaporation rate dependence for titanium dioxide were obtained. The time changes of these constants were also measured.     

Optical constants of polymer coatings in the infrared

The refractive indices and absorption coefficients of fluorocarbon, polymethyl methacrylate, and polyimide were measured in the wavelength range of 2–12 μm. The reflection losses of KRS-5 and CsI windows were reduced successfully by coating fluorocarbon polymers on the surfaces.     

Optical constants of thin oxide films on titanium

Thin oxide films on titanium formed by heating were studied by the ellipsometric method. To obtain the complex refractive index and film thicknesses, the ellipsometric measurements were performed by means of the immersing method: each sample was measured first in air and then in a liquid of known refractive index (in our case CCl₄). The optical constants and the oxide film thickness were computed by means of a computer from two pairs of ellipsometric values. To state the optical constants of clean titanium surface the graphic-computational method was proposed and applied. The measurements were carried out at two wavelengths on oxide films grown in air and dry oxygen by thermal oxidation at temperatures from 150 to 700 °C. It has been shown that when increasing the film thickness the refractive index of the film decreases, whereas the absorption coefficient is independent on the film thickness. Optical constants of oxide films growing in dry oxygen are smaller than those growing in air.     

Optical constants of gold in MOM tunnel junction

The angular distribution of light emitted by Al-AlO-Au diodes was studied. Fast surface plasmon oscillations (SPO) were found in the top metal film above the d-band absorption edge. From the dispersion curve of SPO the optical constants of the Au film were determined and found to differ from literature data.     

Optical properties of in situ doped and undoped titania nanocatalysts and doped titania sol-gel nanofilms

In this paper we present spectroscopic properties of doped and undoped titanium dioxide (TiO₂) as nanofilms prepared by the sol-gel process with rhodamine 6G doping and studied by photoacoustic absorption, excitation and emission spectroscopy. The absorption spectra of TiO₂ thin films doped with rhodamine 6G at very low concentration during their preparation show two absorption bands, one at 2.3 eV attributed to molecular dimmer formation, which is responsible for the fluorescence quenching of the sample and the other at 3.0 eV attributed to TiO₂ absorption, which subsequently yields a strong emission band at 600 nm. The electronic band structure and optical properties of the rutile phase of TiO₂ are calculated employing a fully relativistic, full-potential, linearized, augmented plane-wave (FPLAPW) method within the local density approximation (LDA). Comparison of this calculation with experimental data for TiO₂ films prepared for undoped sol-gels and by sputtering is performed.     

Optical constants of DUV/UV fluoride thin films

High-refractive-index materials LaF3, NdF3, and GdF3 and low-refractive-index materials MgF2, A1F3, and Na3A1F6 single thin films are deposited by a resistive-heating boat at different depositing rates and specific substrate temperatures on single crystal MgF2 substrates. Transmittances of all fluoride thin films are measured using commercial spectrometer in the ambient atmosphere and under vacuum using synchrotron radiation instrument in the wavelength region from 190 to 500 am. The optical constants of these materials are determined by envelope method and iterative algorithm on the basis of transmittance measurements.     

Optical constants of plasmas based on quantum corrected collisions

The well known quantum correction of the cross section for emission of bremsstrahlung (Gaunt-Maue branch apart from Kramers branch) is applied for the Coulomb collision frequency in fully ionized plasmas. The correction of the optical constants was derived and the absorption constant and the real part of the refractive index is calculated for neodymium glass laser radiation in fully ionized hydrogen.     

氟化物材料在深紫外波段的光学常数

研究了紫外领域常用的6种大带隙的氟化物薄膜材料,在氟化镁单晶基底上用热舟蒸发镀制了三种高折射率材料薄膜LaF₃,NdF₃,GdF₃和三种低折射率材料薄膜MgF₂,AlF₃,Na₃AlF₆;用商用lambda900光谱仪测量了它们在190—500 nm范围的透射率光谱曲线;用包络法研究了它们的折射率和消光系数,研究了影响透射率和光学常数的主要因素,给出了6 关键词： 光学常数 包络法 氟化物材料 深紫外