Multilayer Optics Research Articles

Aspedamite, Ideally 12(Fe3+, Fe2+)3Nb4[Th(Nb,Fe3+)12O42] 12, a New Heteropolyniobate Mineral Species from the Herrebokasa Guarry, Aspedammen, Ostfold, Southern Norway: Description and Crystal Structure

Aspedamite, ideally □ 12 (Fe 3+ ,Fe 2+ ) 3 Nb 4 [Th(Nb,Fe 3+ ) 12 O 42 ]{(H 2 O),(OH)} 12 , is a new heteropolyniobate mineral species from the Herrebokasa quarry, Aspedammen, Ostfold, southern Norway. It occurs as small euhedral crystals of dodecahedra and cubes to a maximum of 50 μm across, perched on a white mat of an Al–Nb–Fe–Ti–Ca–K-bearing silicate on a partly altered 12 × 12 × 6 mm crystal of monazite penetrated by plates of columbite-(Fe) and muscovite. Aspedamite is brownish orange with a very pale orange streak and an adamantine luster; it does not fluoresce under ultraviolet light. The Mohs hardness is 3–4, and it is brittle with a hackly fracture. The calculated density is 4.070 g/cm 3 , and the calculated index of refraction is 2.084. Aspedamite is cubic, space group Im 3, a 12.9078(6) A, V 2150.6(3) A 3 , Z = 2. The strongest seven lines in the X-ray powder-diffraction pattern [ d in A( I ) hkl ] are: 9.107(100)011, 2.635(36)224, 2.889(33)024, 1.726(29)246, 3.233(28)004, 3.454(18)123, 4.567(15)022. A chemical analysis with an electron microprobe gave Nb 2 O 5 65.64, Ta 2 O 5 1.78, SiO 2 0.78, ThO 2 5.64, TiO 2 2.15, Fe 2 O 3 10.56, FeO 2.73, MnO 0.82, CaO 0.28, K 2 O 0.16, La 2 O 3 0.52, Ce 2 O 3 1.62, Nd 2 O 3 0.44, H 2 O (calc) 7.20, sum 100.32 wt.%; the H 2 O content was determined by crystal-structure analysis. The empirical formula of aspedamite on the basis of 54 anions with Fe 3+ /(Fe 3+ + Fe 2+ ) = 0.67 (estimated from crystal-chemical arguments) and O(4) = (H 2 O) 9 + (OH) 3 is K 0.09 Ca 0.13 Ce 0.26 La 0.08 Nd 0.07 Fe 2+ 1.00 Mn 0.30 Fe 3+ 3.48 Th 0.56 Ti 4+ 0.71 Si 0.34 Nb 12.98 Ta 0.21 O 42 (H 2 O) 9 (OH) 3 . The crystal structure of aspedamite was solved by direct methods and refined to an R 1 index of 1.6% based on 596 observed reflections collected on a three-circle rotating-anode (Mo K α X-radiation) diffractometer equipped with multilayer optics and an APEX-II detector. The structure is based on the heteropolyanion [ DA 12 O 42 ] ( D = Th, sum A = Nb 9 Fe 3+ 2 Ti), which consists of twelve face- and corner-sharing AO 6 octahedra that surround the [12]-coordinated D cation. There are eight heteropolyanions at the corners of the unit cell, with an additional heteropolyanion at the center, forming an I -centered arrangement. Each heteropolyhedral cluster is decorated by eight B octahedra, each of which bridges two adjacent clusters along the body diagonals of the cell. Further intercluster linkage is provided by the C octahedra, which link pairs of adjacent clusters in the a direction. Aspedamite is isostructural with menezesite.

Refinement of the crystal structure of zoned philipsbornite–hidalgoite from the Tsumeb mine, Namibia, and hydrogen bonding in the D2+G3+3(T5+O4)(TO3OH)(OH)6 alunite structures

AbstractThe crystal structure of zoned philipsbornite – hidalgoite, hexagonal (rhombohedral), Rm , Z = 3: a = 7.1142(4), c = 17.0973(9) A ˚ , V = 749.4(1) Å3, from the Tsumeb mine, Namibia, has been refined to R1 = 1.68% for 301 unique reflections collected on a Bruker D8 three-circle diffractometer equipped with a rotating-anode generator, multilayer optics and an APEX-II CCD detector. Chemical analysis by electron microprobe showed zoned crystals with a rim enriched in S and Fe relative to the core. The core composition is SO3 3.31, As2O5 30.57, Al2O3 23.05, FeO 1.44, PbO 33.94, H2Ocalc 9.58, total 101.79 wt.%, corresponding to Pb0.982+(Al2.92Fe0.132+)(AsO4)[(As0.72S0.27)O3.14(OH)0.85](OH)6; and the rim composition is SO3 8.88, As2O5 22.63, Al2O3 22.90, FeO 2.57, PbO 34.91, H2Ocalc 9.27, total 101.16 wt.%, corresponding to Pb0.992+(Al2.85Fe0.232+)(AsO4)[(As0.25S0.70)O3.30(OH)0.50](OH)6. Philipsbornite – hidalgoite has the alunite-type structure, sheets of corner-sharing octahedra, decorated on top and bottom by [(As,S)O4] and (AsO3OH) tetrahedra, that are linked into a three-dimensional structure by [12]-coordinated Pb2+ cations and hydrogen bonds. A new hydrogen-bonding scheme for the D2+G33+(T5+O4)(TO3OH)(OH)6 minerals is proposed.

Precision imaging multilayer optics for soft X-rays and extreme ultraviolet bands

Optical methods that provide high diffraction image quality with a spatial resolution of several to tens of nanometers and are in demand in such areas as projection lithography, X-ray microscopy, astrophysics, and fundamental research on the interaction of matter (vacuum) with ultrahigh (– W cm) electromagnetic fields are reviewed in terms of fabrication and testing technologies and possible use in the – nm wavelength range. The current worldwide status of and recent achievements by the Institute for Physics of Microstructures of the Russian Academy of Sciences (RAS) in the field are discussed.

Compact x-ray microscope for the water window based on a high brightness laser plasma source

We present a laser plasma based x-ray microscope for the water window employing a high-average power laser system for plasma generation. At 90 W laser power a brightness of 7.4 x 10(11) photons/(s x sr x μm(2)) was measured for the nitrogen Lyα line emission at 2.478 nm. Using a multilayer condenser mirror with 0.3 % reflectivity 10(6) photons/(μm(2) x s) were obtained in the object plane. Microscopy performed at a laser power of 60 W resolves 40 nm lines with an exposure time of 60 s. The exposure time can be further reduced to 20 s by the use of new multilayer condenser optics and operating the laser at its full power of 130 W.

SENSITIVITY OF STACKED IMAGING DETECTORS TO HARD X-RAY POLARIZATION

The development of multi-layer optics which allow to focus photons up to 100 keV and more promises an enormous jump in sensitivity in the hard X-ray energy band. This technology is already planned to be exploited by future missions dedicated to spectroscopy and imaging at energies >10 keV, e.g. Astro-H and NuSTAR. Nevertheless, our understanding of the hard X-ray sky would greatly benefit from carrying out contemporaneous polarimetric measurements, because the study of hard spectral tails and of polarized emission often are two complementary diagnostics of the same non-thermal and acceleration processes. At energies above a few tens of keV, the preferred technique to detect polarization involves the determination of photon directions after a Compton scattering. Many authors have asserted that stacked detectors with imaging capabilities can be exploited for this purpose. If it is possible to discriminate those events which initially interact in the first detector by Compton scattering and are subsequently absorbed by the second layer, the direction of scattering is singled out from the hit pixels in the two detectors. In this paper we give the first detailed discussion of the sensitivity of such a generic design to the X-ray polarization. The efficiency and the modulation factor are calculated analytically from the geometry of the instruments and then compared with the performance as derived by means of Geant4 Monte Carlo simulations.

Multilayer and Multidomain Resilience in Optical Networks

This paper details approaches to resilience in optical multilayer and multidomain networks. Principal challenges and solutions have been described using exemplary settings and models. In addition, we have also shared an outlook to future research topics within this paper.

Grazing-incidence in-plane X-ray diffraction on ultra-thin organic films using standard laboratory equipment

A novel grazing-incidence in-plane X-ray diffraction setup based on a commercial four-circle diffractometer with a sealed-ceramic copper X-ray tube, upgraded with parabolic graded multilayer X-ray optics and a one-dimensional position-sensitive detector, is presented. The high potential of this setup is demonstrated by a phase analysis study of pentacene thin films and the determination of in-plane lattice constants of pentacene mono- and multilayers. The quality of the results compare well to studies performed at synchrotron radiation facilities.

Davidlloydite, ideally Zn3(AsO4)2(H2O)4, a new arsenate mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia: description and crystal structure

AbstractDavidlloydite, ideally Zn3(AsO4)2(H2O)4, is a new supergene mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia. It occurs as elongated prisms (∼10:1 length-to-width ratio) that are flattened on {010}, and up to 100 × 20 × 10 μm in size. The crystals occur as aggregates (up to 500 μm across) of subparallel to slightly diverging prisms lying partly on and partly embedded in fine-grained calcioandyrobertsite. Crystals are prismatic along [001] and flattened on {010}, and show the forms {010} dominant and {100} subsidiary. Davidlloydite is colourless with a white streak and a vitreous lustre; it does not fluoresce under ultraviolet light. The cleavage is distinct on {010}, and no parting or twinning was observed. The Mohs hardness is 3 – 4. Davidlloydite is brittle with an irregular to hackly fracture. The calculated density is 3.661 g cm–3. Optical properties were measured with a Bloss spindle stage for the wavelength 590 nm using a gel filter. The indices of refraction are α = 1.671, β = 1.687, γ = 1.695, all ±0.002; the calculated birefringence is 0.024; 2Vobs = 65.4(6)°, 2Vcalc = 70°; the dispersion is r < v, weak; pleochroism was not observed. Davidlloydite is triclinic, space group P1, with a = 5.9756(4), b = 7.6002(5), c = 5.4471(4) Å, α = 84.2892(9), β = 90.4920(9), γ = 87.9958(9)°, V = 245.99(5) Å3, Z = 1 and a:b:c = 0.7861:1:0.7167. The seven strongest lines in the X-ray powder diffraction pattern [listed as d (Å), I, (hkl)] are as follows: 4.620, 100, (011, 10); 7.526, 71, (010); 2.974, 49, (200, 01); 3.253, 40, (021, 120); 2.701, 39, (10, 002, 1); 5.409, 37, (001); 2.810, 37, (210). Chemical analysis by electron microprobe gave As2O5 43.03, ZnO 37.95, CuO 5.65, H2O(calc) 13.27, sum 99.90 wt.%. The H2O content and the valence state of As were determined by crystal structure analysis. On the basis of 12 anions with H2O = 4 a.p.f.u., the empirical formula is (Zn2.53Cu0.39)Σ2.92As2.03O8(H2O)4.The crystal structure of davidlloydite was solved by direct methods and refined to an R1 index of 1.51% based on 1422 unique observed reflections collected on a three-circle rotating-anode (MoKα radiation) diffractometer equipped with multilayer optics and an APEX-II detector. In the structure of davidlloydite, sheets of corner-sharing (As5+O4) and (ZnO4) tetrahedra are linked by ZnO2(H2O)4 octahedra. The structure is related to that of parahopeite.

Natrotitanite, ideally (Na0.5Y0.5)Ti(SiO4)O, a new mineral from the Verkhnee Espe deposit, Akjailyautas mountains, Eastern Kazakhstan district, Kazakhstan: description and crystal structure

AbstractNatrotitanite, ideally (Na0.5Y0.5)Ti(SiO4)O, is a new mineral from the Verkhnee Espe rare-element deposit at the northern exo-contact of the Akjailyautas granite massif in the northern part of the Tarbagatai mountain range, Eastern Kazakhstan. Both the mineral and the name have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2010-033). Star-shaped aggregates of small short prisms of yellow or yellowish white (Na,Y,REE)-bearing titanite rimmed by thin (∼2 μm) rims of natrotitanite are embedded in yttrium-bearing fluorite and replace narsarsukite. Associated minerals are microcline, albite, quartz, riebeckite, aegirine, biotite, astrophyllite, rutile, zircon and elpidite. Natrotitanite is milky white to yellowish grey, transparent to translucent, and has a white streak and a vitreous lustre. It shows pale orange cathodoluminescence but does not fluoresce under ultraviolet light. It shows no cleavage or parting, and is brittle; the calculated density is 3.833 g cm–3. The indices of refraction, measured with the Bloss spindle stage for the wavelength 590 nm using a gel filter, are α = 1.904, γ = 2.030, and these values are in accord with the mean refractive index, 1.988, calculated from the Gladstone-Dale relation. Natrotitanite is monoclinic,C2/c,a= 6.5691(2),b= 8.6869(3),c= 7.0924(2) Å, β = 114.1269(4)°,V= 369.4(2) Å3,Z= 4,a:b:c= 0.7562:1: 0.8164. The seven strongest lines in the X-ray powder diffraction pattern [in the orderd(Å),I, (hkl)] are as follows: 2.597, 10, (130); 3.248, 8, (11); 2.994, 6, (200); 1.641, 4, (330); 4.941, 3, (110); 1.498, 3, (400); 2.273, 3, (11). Chemical analysis by electron microprobe gave Nb2O51.28, SiO227.83, TiO235.00, SnO20.57, V2O30.36, Fe2O30.23, Y2O37.87, Ce2O30.83, Sm2O30.26, Gd2O30.46, Tb2O30.17, Dy2O32.45, Ho2O30.16, Er2O32.24, Tm2O30.50, Yb2O32.53, Nd2O30.35, Lu2O30.28, MnO 0.33, CaO 8.16, Na2O 5.55, F 1.52 O ≡ F –0.64, sum 98.71 wt.%. The resulting empirical formula is (Na0.39Ca0.32Y0.15Dy0.03Yb0.03Er0.03Ce0.01Ho0.01Tm0.01Gd0.01Nd0.01)Σ1.00(Ti0.95Nb0.02Sn0.01Fe3+0.01Mn0.01V0.01)Σ1.01Si1.01O4.00(O0.83F0.17), calculated on the basis of 3 cations per formula unit. The general formula is written as (Na,Ca,Y,REE)TiSiO4(O,F), and the endmember formula is (Na0.5Y0.5)Ti(SiO4)O.The crystal structure of a composite optically continuous crystal of natrotitanite and (Na, Y)-bearing titanite was mounted on a Bruker D8 three-circle diffractometer equipped with a rotating anode generator (MoKα radiation), a multi-layer optics incident-beam path and an APEX-II CCD detector. The crystal structure was refined in space groupC2/cto a finalR1index of 1.8%. Natrotitanite is isostructural with titanite, (Na + Y +REE) replacing Ca at theCasite in the titanite structure.

Feasibility study of broadband efficient “water window” source

We demonstrate a table-top broadband emission water window source based on laser-produced high-Z plasmas. Resonance emission from multiply charged ions merges to produce intense unresolved transition arrays (UTAs) in the 2–4 nm region, extending below the carbon K edge (4.37 nm). Arrays resulting from n=4-n=4 transitions are overlaid with n=4-n=5 emission and shift to shorter wavelength with increasing atomic number. An outline of a microscope design for single-shot live cell imaging is proposed based on a bismuth plasma UTA source, coupled to multilayer mirror optics.

Прецизионная изображающая многослойная оптика для мягкого рентгеновского и экстремального ультрафиолетового диапазонов

Прецизионная изображающая многослойная оптика для мягкого рентгеновского и экстремального ультрафиолетового диапазонов

Laboratory cryo soft X-ray microscopy

Lens-based water-window X-ray microscopy allows two- and three-dimensional (2D and 3D) imaging of intact unstained cells in their near-native state with unprecedented contrast and resolution. Cryofixation is essential to avoid radiation damage to the sample. Present cryo X-ray microscopes rely on synchrotron radiation sources, thereby limiting the accessibility for a wider community of biologists. In the present paper we demonstrate water-window cryo X-ray microscopy with a laboratory-source-based arrangement. The microscope relies on a λ=2.48-nm liquid-jet high-brightness laser-plasma source, normal-incidence multilayer condenser optics, 30-nm zone-plate optics, and a cryo sample chamber. We demonstrate 2D imaging of test patterns, and intact unstained yeast, protozoan parasites and mammalian cells. Overview 3D information is obtained by stereo imaging while complete 3D microscopy is provided by full tomographic reconstruction. The laboratory microscope image quality approaches that of the synchrotron microscopes, but with longer exposure times. The experimental image quality is analyzed from a numerical wave-propagation model of the imaging system and a path to reach synchrotron-like exposure times in laboratory microscopy is outlined.

Infrared reflectance and transmission spectra in II-VI alloys and superlattices

Room temperature measurements of the far-infrared (FIR) reflectance spectra are reported for the polar optical phonons in a series of bulk Cd${}_{x}$Zn${}_{1\ensuremath{-}x}$Te (0 \ensuremath{\le} $x$ \ensuremath{\le} 1) and CdSe${}_{x}$Te${}_{1\ensuremath{-}x}$ (0 $x$ \ensuremath{\le} 0.35) crystals grown by Bridgman technique. The composition-dependent spectra exhibited many fundamental aspects of lattice vibrations, while the results of long-wavelength optical modes for the end member binary compounds displayed phonon values in good agreement with the existing inelastic neutron scattering and/or Raman spectroscopy data. Using a standard methodology of multilayer optics with effective-medium dielectric tensors, we simulated the FIR transmission and reflectivity spectra at oblique incidence (Berreman's effect) in many II-VI free-standing thin films, epilayers and superlattices. Berreman's approach provided us with a strong basis for analyzing the infrared experimental data and offered an effective means of estimating the zone-center transverse and longitudinal optical (${\ensuremath{\omega}}_{\mathrm{TO}}$, ${\ensuremath{\omega}}_{\mathrm{LO}}$) phonon frequencies in polar-semiconductor thin films and heterostructure materials of increasing technological importance.

Determination of Director Profile in the Vertical Alignment Nematic Liquid Crystal Cell by the Full Leaky Guided Mode Technique

By means of the full leaky guided mode technique, the transmittance of the full leaky waveguide geometry which consists of pyramid, matching fluid of refractivity, the vertical alignment nematic liquid crystal cell are investigated experimentally. The experimental curves with different voltages between polarization-conserving transmittance Tss and the internal angle (the angle of incidence for which light is incident on the vertical alignment liquid crystal cell) are obtained. Comparing these experimental curves with the theoretical curves obtained from multi-layer optics theory, the director profile of vertical alignment nematic liquid crystal cell for different voltages is determined.

Loss of hydrogen atoms in H2 plasma on the surfaces of materials used in EUV lithography

Lowpressure hydrogen is an important component of the working medium in extreme ultraviolet (EUV) projection lithography. Under the action of EUV photons and fast secondary electrons on the gas medium, plasma and atomic hydrogen, actively interacting with the surface, are produced. This interaction is very important, because it largely determines the lifetime of the multilayered EUV optics. In this study, the loss of atomic hydrogen under the conditions of a low pressure (<10 Torr) RF plasma discharge on the sur� faces of materials used in EUV lithography is investigated. The surface loss probabilities of H atoms on these materials are measured. It is shown that surface recombination of atomic hydrogen goes according to the Eley-Rideal mechanism via direct recombination of H atoms from the gas phase with chemically and phys� ically adsorbed atoms. In this case, the surface recombination probability is mainly determined by the density of chemical adsorption sites. The density of adsorption sites and the desorption energy of H atoms are esti� mated. The desorption energy of physically adsorbed H atoms on pure metal surfaces (or surfaces exposed to plasma) is about 0.5 eV, and the density of sorption sites is close to the surface density of atoms. This results in a high loss probability of H atoms on metals (~0.1). Therefore, to provide efficient transportation of hydro� gen atoms, it is necessary to use materials with the lowest loss probability of H atoms, i.e., dielectrics.

Electric-field-induced fabrication of covalently linked second-order nonlinear optical multilayer films on nonconductive substrates

A highly stable second-order nonlinear optical multilayer film was constructed on insulating substrates using the electric-field-induced layer-by-layer assembly technique. The substrates used in this method could be arbitrary. In another, the substrates could be modified with polyanion solution by spin coating as cladding layer. Then, the nonlinear optical multilayer films were assembled on the cladding layer directly by the electric-field-induced layer-by-layer assembly technique. The resulting cross-linked multilayer films fabricated by this method displayed high optical transparency, good thermal stability, and excellent nonlinear optical properties which can be made into waveguide devices directly.

Multilayer optics for novel sources in X-ray analytics

Multilayer optics for novel sources in X-ray analytics

Laboratory X-ray microscopy for high-resolution imaging of environmental colloid structure

Transmission X-ray microscopy is a uniquely suited technique for studies of environmental colloids since it allows imaging in aqueous media with high spatial resolution, presently down to the 20nm range. Such nano-scale morphological description of these high-specific-surface-area compounds show promise for improved understanding of soils, sediments or groundwater aquifers. However, present high-quality X-ray microscopes are located at synchrotron radiation facilities resulting in limited applicability and accessibility for colloid scientists. Here we investigate the applicability of a laboratory-scale transmission X-ray microscope for studies of colloids of the environment. The microscope is based on a laser-plasma source in combination with multilayer and zone plate optics. Samples are held at atmospheric pressure in their natural wet state. We show images revealing the nano-scale morphology of the clay nontronite, soils such as chernozem and luvisol, and the mineral hematite, an iron oxide. Comparative studies of dried substances clearly show the need for imaging in the wet state. The image quality approaches that of synchrotron-based microscopes, albeit at longer exposure times. Stereo imaging is investigated as a means for giving 3D information with shorter exposure times than tomography requires. Finally the future development of the laboratory X-ray microscope is discussed, especially with regard to the reduction of exposure times.

Thermal noise and coating optimization in multilayer dielectric mirrors

Optical multilayer coatings of high-reflective mirrors significantly determine the properties of Fabry-Perot resonators. Thermal (Brownian) noise in these coatings produce excess phase noise which can seriously degrade the sensitivity of high-precision measurements with these cavities, in particular in laser gravitational-wave antennas (for example project LIGO), where at the current stage it is one of the main limiting factors. We present a method to calculate this effect accurately and analyze different strategies to diminish it by optimizing the coating. Traditionally this noise is calculated as if the beam is reflected from the surface of the mirror fluctuating due to the sums of the fluctuations of each layer. However the beam in fact penetrates a coating and Brownian expansion of the layers leads to dephasing of interference in the coating and consequently to additional change in reflected phase. Fluctuations in the thickness of a layer change the strain in the medium and hence due to photoelastic effect change the refractive index of this layer. This additional effect should be also considered. It is possible to make the noise smaller preserving the reflectivity by changing the total number of layers and thicknesses of high and low refractive ones. We show how this optimized coating may be constructed analytically rather then numerically as before. We also check the possibility to use internal resonant layers and optimized cap layer to decrease the thermal noise.

Low-energy contamination of Mo microsource X-ray radiation: analysis and solution of the problem

In recent years, microsource sealed tubes in combination with multilayer optics have been adopted in many crystallography laboratories for very low power X-ray generation, monochromatization and high-brilliance microfocusing. All these factors allow high-performance experiments on a laboratory scale. However, a fundamental defect of this technology has been discovered, namely a significant contamination of the characteristic radiation by low-energy photons. Some simple experiments are reported, showing that the contamination can significantly reduce the accuracy of the measured intensities, especially when Mo Kα radiation is used. A simple and economic solution to the problem is proposed: an aluminium filter approximately 100 µm thick, which efficiently removes the low-energy contaminant photons.