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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 1,297 records · Page 72
All sourcesNASA NTRSDOE OSTI
DOE OSTI2013

Effects of boron dopants of Si (001) substrates on formation of Ge layers by sputter epitaxy method

The formation of Ge layers on boron-doped Si (001) substrates by our sputter epitaxy method has been investigated. The surface morphology of Ge layers grown on Si substrates depends on the substrate resistance, and flat Ge layers are obtained on Si substrates with 0.015 Ω cm resistivity. Highly boron-doped Si substrates cause a transition in the dislocation structure from complex dislocations with 60° dislocation glide planes to 90° pure-edge dislocations, resulting in the formation of flat Ge layers. Furthermore, we have found that the surface morphology of the Ge layers improves with increasing Ge layer thickness. Ge atoms migrating on the deposited Ge layers tend to position themselves at the reactive sites, where the reactivity is related to the number of bonding contacts between the Ge atom and the surface. This modifies the surface morphology, resulting in a flatter surface. Boron dopants together with the sputter epitaxy method effectively suppress the growth of Ge islands and result in the formation of flat Ge layers.

36 MATERIALS SCIENCE↗
DOE OSTI2014

Quality-enhanced In{sub 0.3}Ga{sub 0.7}As film grown on GaAs substrate with an ultrathin amorphous In{sub 0.6}Ga{sub 0.4}As buffer layer

Using low-temperature molecular beam epitaxy, amorphous In{sub 0.6}Ga{sub 0.4}As layers have been grown on GaAs substrates to act as buffer layers for the subsequent epitaxial growth of In{sub 0.3}Ga{sub 0.7}As films. It is revealed that the crystallinity of as-grown In{sub 0.3}Ga{sub 0.7}As films is strongly affected by the thickness of the large-mismatched amorphous In{sub 0.6}Ga{sub 0.4}As buffer layer. Given an optimized thickness of 2 nm, this amorphous In{sub 0.6}Ga{sub 0.4}As buffer layer can efficiently release the misfit strain between the In{sub 0.3}Ga{sub 0.7}As epi-layer and the GaAs substrate, trap the threading and misfit dislocations from propagating to the following In{sub 0.3}Ga{sub 0.7}As epi-layer, and reduce the surface fluctuation of the as-grown In{sub 0.3}Ga{sub 0.7}As, leading to a high-quality In{sub 0.3}Ga{sub 0.7}As film with competitive crystallinity to that grown on GaAs substrate using compositionally graded In{sub x}Ga{sub 1-x}As metamorphic buffer layers. Considering the complexity of the application of the conventional In{sub x}Ga{sub 1-x}As graded buffer layers, this work demonstrates a much simpler approach to achieve high-quality In{sub 0.3}Ga{sub 0.7}As film on GaAs substrate and, therefore, is of huge potential for the InGaAs-based high-efficiency photovoltaic industry.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Manipulation by exchange coupling in layered magnetic structures

Exchange coupling in magnetic heterostructures can be modified via introduction of additional magnetic spacer layers at the interfaces. The magnetic characteristics and the spacer layer thickness determine the functional properties of the whole system. We show that the hysteresis loop area of trilayer spring magnets with two different soft magnetic layers (s1, s2) and one hard magnetic layer (h) with the sequence s1/s2/h can be increased as compared to both bilayer structures s1/h and s2/h with the same total thickness of the soft layers and for definite thickness ratios of the soft layers and their sequences. For ferrimagnetic spin valves, the perpendicular exchange bias effect can be tuned via the thickness of non-magnetic spacer layers at the interface, which determine the exchange coupling between ferrimagnets. A simple quasi one-dimensional phenomenological model is able to describe the magnetic hysteresis of even complex layered structures and to predict optimal geometrical and magnetic parameters of such heterostructures.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Interplay between out-of-plane anisotropic L1{sub 1}-type CoPt and in-plane anisotropic NiFe layers in CoPt/NiFe exchange springs

Films of L1{sub 1}-type CoPt/NiFe exchange springs were grown with different NiFe (Permalloy) layer thickness (t{sub NiFe} = 0–10 nm). X-ray diffraction analysis reveals that the characteristic peak position of NiFe(111) is not affected by the CoPt-layer—confirming the absence of any inter-diffusion between the CoPt and NiFe layers. Magnetic studies indicate that the magnetization orientation of NiFe layer can be tuned through varying t{sub NiFe} and the perpendicular magnetic anisotropy of L1{sub 1}-type CoPt/NiFe films cannot sustain for t{sub NiFe} larger than 3.0 nm due to the existence of exchange interaction at the interface of L1{sub 1}-CoPt and NiFe layers. Magnetic force microscopy analysis on the as-grown samples shows the changes in morphology from maze-like domains with good contrast to hazy domains when t{sub NiFe} ≥ 3.0 nm. The three-dimensional micro-magnetic simulation results demonstrate that the magnetization orientation in NiFe layer is not uniform, which continuously increases from the interface to the top of NiFe layer. Furthermore, the tilt angle of the topmost NiFe layers can be changed over a very wide range from a small number to about 75° by varying t{sub NiFe} from 1 to 10 nm. It is worth noting that there is an abrupt change in the magnetization direction at the interface, for all the t{sub NiFe} investigated. The results of present study demonstrate that the tunable tilted exchange springs can be realized with L1{sub 1}-type CoPt/NiFe bilayers for future applications in three-axis magnetic sensors or advanced spintronic devices demanding inclined magnetic anisotropy.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2014

Comprehensive study of Al-induced layer-exchange growth for orientation-controlled Si crystals on SiO{sub 2} substrates

Orientation-controlled crystalline Si films on insulating substrates are strongly required to achieve high-performance thin-film devices for next-generation electronics. We have comprehensively investigated the layer-exchange kinetics of Al-induced crystallization (AIC) in stacked structures, i.e., amorphous-Si/Al-oxide/Al/SiO{sub 2}-substrates, as a function of the air-exposure time of Al surfaces (t{sub air}: 0–24 h) to form Al-oxide interface-layers, the thickness of Al and Si layers (d{sub Al,} d{sub Si}: 50–200 nm), the annealing temperature (450–500 °C), and the annealing time (0–50 h). It has been clarified that longer t{sub air} (>60 min) and/or thinner d{sub Al} and d{sub Si} (<50 nm) lead to the (111) oriented growth; in contrast, shorter t{sub air} (<60 min) and/or thicker d{sub Al} and d{sub Si} (>100 nm) lead to the (100) oriented growth. No correlation between the annealing temperature and the crystal orientation is observed. Detailed analysis reveals that the layer-exchange kinetics are dominated by “supply-limited” processing, i.e., diffusion of Si atoms into Al layers through Al-oxide layer. Based on the growth rate dependent Si concentration profiles in Al layers, and the free-energy of Si at Al-oxide/Al or Al/SiO{sub 2} interfaces, a comprehensive model for layer-exchange growth is proposed. This well explains the experimental results of not only Si-AIC but also another material system such as gold-induced crystallization of Ge. In this way, a growth technique achieving the orientation-controlled Si crystals on insulating substrates is established from both technological and scientific points of view.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Optical layer development for thin films thermal conductivity measurement by pulsed photothermal radiometry

Measurement of thermal conductivity and volumetric specific heat of optically transparent thin films presents a challenge for optical-based measurement methods like pulsed photothermal radiometry. We present two approaches: (i) addition of an opaque optical layer to the surface and (ii) approximate correction of the mathematical model to incorporate semitransparency of the film. Different single layer and multilayer additive optical layers were tested. The materials of the optical layers were chosen according to analysis and measurement of their optical properties: emissivity and absorption coefficient. Presented are thermal properties’ measurement results for 6 different thin films with wide range of thermal conductivity in three configurations of surface: as deposited, added Ti layer, and added Ti/TiAlSiN layer. Measurements were done in dependence on temperature from room temperature to 500 °C. The obtained thermal effusivity evolution in time after the laser pulse shows different effects of the surface layers: apparent effusivity change and time delay. Suitability of different measurement configurations is discussed and results of high temperature testing of different optical layers are presented.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2015

A charge carrier transport model for donor-acceptor blend layers

Highly efficient organic solar cells typically comprise donor-acceptor blend layers facilitating effective splitting of excitons. However, the charge carrier mobility in the blends can be substantially smaller than in neat materials, hampering the device performance. Currently, available mobility models do not describe the transport in blend layers entirely. Here, we investigate hole transport in a model blend system consisting of the small molecule donor zinc phthalocyanine (ZnPc) and the acceptor fullerene C{sub 60} in different mixing ratios. The blend layer is sandwiched between p-doped organic injection layers, which prevent minority charge carrier injection and enable exploiting diffusion currents for the characterization of exponential tail states from a thickness variation of the blend layer using numerical drift-diffusion simulations. Trap-assisted recombination must be considered to correctly model the conductivity behavior of the devices, which are influenced by local electron currents in the active layer, even though the active layer is sandwiched in between p-doped contacts. We find that the density of deep tail states is largest in the devices with 1:1 mixing ratio (E{sub t} = 0.14 eV, N{sub t} = 1.2 × 10{sup 18 }cm{sup −3}) directing towards lattice disorder as the transport limiting process. A combined field and charge carrier density dependent mobility model are developed for this blend layer.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

Effects of disorder state and interfacial layer on thermal transport in copper/diamond system

The characterization of Cu/diamond interface thermal conductance (h{sub c}) along with an improved understanding of factors affecting it are becoming increasingly important, as Cu-diamond composites are being considered for electronic packaging applications. In this study, ∼90 nm thick Cu layers were deposited on synthetic and natural single crystal diamond substrates. In several specimens, a Ti-interface layer of thickness ≤3.5 nm was sputtered between the diamond substrate and the Cu top layer. The h{sub c} across Cu/diamond interfaces for specimens with and without a Ti-interface layer was determined using time-domain thermoreflectance. The h{sub c} is ∼2× higher for similar interfacial layers on synthetic versus natural diamond substrate. The nitrogen concentration of synthetic diamond substrate is four orders of magnitude lower than natural diamond. The difference in nitrogen concentration can lead to variations in disorder state, with a higher nitrogen content resulting in a higher level of disorder. This difference in disorder state potentially can explain the variations in h{sub c}. Furthermore, h{sub c} was observed to increase with an increase of Ti-interface layer thickness. This was attributed to an increased adhesion of Cu top layer with increasing Ti-interface layer thickness, as observed qualitatively in the current study.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2015

On the use of a charged tunnel layer as a hole collector to improve the efficiency of amorphous silicon thin-film solar cells

A new concept, using a negatively charged tunnel layer as a hole collector, is proposed and theoretically investigated for application in amorphous silicon thin-film solar cells. The concept features a glass/transparent conductive oxide/ultra-thin negatively charged tunnel layer/intrinsic a-Si:H/n-doped a-Si:H/metal structure. The key feature of this so called t{sup +}-i-n structure is the introduction of a negatively charged tunnel layer (attracting holes from the intrinsic absorber layer), which substitutes the highly recombination active p-doped a-Si:H layer in a conventional p-i-n configuration. Atomic layer deposited aluminum oxide (ALD AlO{sub x}) is suggested as a potential candidate for such a tunnel layer. Using typical ALD AlO{sub x} parameters, a 27% relative efficiency increase (i.e., from 9.7% to 12.3%) is predicted theoretically for a single-junction a-Si:H solar cell on a textured superstrate. This prediction is based on parameters that reproduce the experimentally obtained external quantum efficiency and current-voltage characteristics of a conventional processed p-i-n a-Si:H solar cell, reaching 9.7% efficiency and serving as a reference. Subsequently, the p-doped a-Si:H layer is replaced by the tunnel layer (studied by means of numerical device simulation). Using a t{sup +}-i-n configuration instead of a conventional p-i-n configuration will not only increase the short-circuit current density (from 14.4 to 14.9 mA/cm{sup 2}, according to our simulations), it also enhances the open-circuit voltage and the fill factor (from 917 mV to 1.0 V and from 74% to 83%, respectively). For this concept to work efficiently, a high work function front electrode material or a high interface charge is needed.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Framework to predict optimal buffer layer pairing for thin film solar cell absorbers: A case study for tin sulfide/zinc oxysulfide

An outstanding challenge in the development of novel functional materials for optoelectronic devices is identifying suitable charge-carrier contact layers. Herein, we simulate the photovoltaic device performance of various n-type contact material pairings with tin(II) sulfide (SnS), a p-type absorber. The performance of the contacting material, and resulting device efficiency, depend most strongly on two variables: conduction band offset between absorber and contact layer, and doping concentration within the contact layer. By generating a 2D contour plot of device efficiency as a function of these two variables, we create a performance-space plot for contacting layers on a given absorber material. For a simulated high-lifetime SnS absorber, this 2D performance-space illustrates two maxima, one local and one global. The local maximum occurs over a wide range of contact-layer doping concentrations (below 10{sup 16 }cm{sup −3}), but only a narrow range of conduction band offsets (0 to −0.1 eV), and is highly sensitive to interface recombination. This first maximum is ideal for early-stage absorber research because it is more robust to low bulk-minority-carrier lifetime and pinholes (shunts), enabling device efficiencies approaching half the Shockley-Queisser limit, greater than 16%. The global maximum is achieved with contact-layer doping concentrations greater than 10{sup 18 }cm{sup −3}, but for a wider range of band offsets (−0.1 to 0.2 eV), and is insensitive to interface recombination. This second maximum is ideal for high-quality films because it is more robust to interface recombination, enabling device efficiencies approaching the Shockley-Queisser limit, greater than 20%. Band offset measurements using X-ray photoelectron spectroscopy and carrier concentration approximated from resistivity measurements are used to characterize the zinc oxysulfide contacting layers in recent record-efficiency SnS devices. Simulations representative of these present-day devices suggest that record efficiency SnS devices are optimized for the second local maximum, due to low absorber lifetime and relatively well passivated interfaces. By employing contact layers with higher carrier concentrations and lower electron affinities, a higher efficiency ceiling can be enabled.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

A comparative density functional study on electrical properties of layered penta-graphene

We present a comparative study of the influence of the number of layers, the biaxial strain in the range of −3% to 3%, and the stacking misalignments on the electronic properties of a new 2D carbon allotrope, penta-graphene (PG), based on hybrid-functional method within the density functional theory (DFT). In comparison with local exchange-correlation approximation in the DFT, the hybrid-functional provides an accurate description on the degree of p{sub z} orbitals localization and bandgap. Importantly, the predicted bandgap of few-layer PG has a weak layer dependence. The bandgap of monolayer PG is 3.27 eV, approximately equal to those of GaN and ZnO; and the bandgap of few-layer PG decreases slowly with the number of layers (N) and converge to 2.57 eV when N ≥ 4. Our calculations using HSE06 functional on few-layer PG reveal that bandgap engineering by stacking misalignment can further tune the bandgap down to 1.37 eV. Importantly, there is no direct-to-indirect bandgap transition in PG by varying strain, layer number, and stacking misalignment. Owing to its tunable, robustly direct, and wide bandgap characteristics, few-layer PG is promising for optoelectronic and photovoltaic applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

High-performance ultraviolet detection and visible-blind photodetector based on Cu{sub 2}O/ZnO nanorods with poly-(N-vinylcarbazole) intermediate layer

This study reports a high-performance hybrid ultraviolet (UV) photodetector with visible-blind sensitivity fabricated by inserting a poly-(N-vinylcarbazole) (PVK) intermediate layer between low-cost processed Cu{sub 2}O film and ZnO nanorods (NRs). The PVK layer acts as an electron-blocking/hole-transporting layer between the n-ZnO and p-Cu{sub 2}O films. The Cu{sub 2}O/PVK/ZnO NR photodetector exhibited a responsivity of 13.28 A/W at 360 nm, a high detectivity of 1.03 × 10{sup 13} Jones at a low bias of −0.1 V under a low UV light intensity of 24.9 μW/cm{sup 2}. The photo-to-dark current ratios of the photodetector with and without the PVK intermediate layer at a bias of −0.5 V are 1.34 × 10{sup 2} and 3.99, respectively. The UV-to-visible rejection ratios (R{sub 360 nm}/R{sub 450 nm}) are 350 and 1.735, respectively. Several features are demonstrated: (a) UV photo-generated holes at the ZnO NRs can effectively be transported through the PVK layer to the p-Cu{sub 2}O layer; (b) the insertion of a PVK buffer layer significantly minimizes the reverse-bias leakage current, which leads to a larger amplification of the photocurrent; and (c) the PVK buffer layer greatly improves the UV-to-visible responsivity ratio, allowing the device to achieve high UV detection sensitivity at a low bias voltage using a very low light intensity.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Effect of layer thickness on the properties of nickel thermal sprayed steel

Thermal arc spray nickel coating is widely used for decorative and functional applications, by improving corrosion resistance, wear resistance, heat resistence or by modifying other properties of the coated materials. There are several properties have been studied. Layer thickness of nickel thermal sprayed steel may be make harder the substrate surface. In this study, the effect of layer thickness of nickel thermal sprayed steel has been investigated. The rectangular substrate specimens were coated by Ni–5 wt.% Al using wire arc spray method. The thickness of coating layers were in range from 0.4 to 1.0 mm. Different thickness of coating layers were conducted to investigate their effect on hardness and morphology. The coating layer was examined by using microvickers and scanning electron microscope with EDX attachment. Generally, the hardness at the interface increased with increasing thickness of coating layers for all specimens due to higher heat input during spraying process. Morphology analysis result that during spraying process aluminum would react with surrounding oxygen and form aluminum oxide at outer surface of splat. Moreover, porosity was formed in coating layers. However, presence porosity is not related to thickness of coating material. The thicker coating layer resulted highesr of hardness and bond strength.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Intra- and inter-layer charge redistribution in biased bilayer graphene

We investigate the spatial redistribution of the electron density in bilayer graphene in the presence of an interlayer bias within density functional theory. It is found that the interlayer charge redistribution is inhomogeneous between the upper and bottom layers and the transferred charge from the upper layer to the bottom layer linearly increases with the external voltage which further makes the gap at K point linearly increase. However, the band gap will saturate to 0.29 eV in the strong-field regime, but it displays a linear field dependence at the weak-field limit. Due to the AB-stacked way, two carbon atoms per unit cell in the same layer are different and there is also a charge transfer between them, making the widths of π valence bands reduced. In the bottom layer, the charge transfers from the direct atoms which directly face another carbon atom to the indirect atoms facing the center of the hexagon on the opposite layer, while the charge transfers from the indirect atoms to the direct atoms in the upper layer. Furthermore, there is a diploe between the upper and bottom layers which results in the reduction of the interlayer hopping interaction.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2016

The influence of layers number on the structure and ferroelectric properties of BZT films

In recent study, the number of BaZrTiO{sub 3} layers were successively deposited on the Si-substrate by spin-coating process. The increasing of layers number affects the films structure which has been observed in XRD, while the ferroelectric properties have been analyzed by Sawyer-Tower. Perovskite tetragonal is observed in all films by the c-a axis ratio around 1.002 to 1.018, and the crystallite sizes were calculated from 75 nm to 129 nm. The maximum polarization value was found to be decreased during the increase of numbers of layers from 3 to 4 layers. On the contrary, the value was noticeably increased to the highest value when 5 layers film was applied. The highest maximum polarization were recorded at 31.68 µC/cm{sup 2} and 34.12 µC/cm{sup 2} respectively for 5 layer BZT films in each 8 at.% and 10 at.% Zr content under electrical fields injection as triangle signal of Alternating Current (AC) 50 V/60 Hz. As the number of layers increases, the polarization field magnitude is significantly decreased. The general results of structure and ferroelectric properties of BZT films have been studied in the influence of layers number to enhance the electrical behavior.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Interlayer exchange coupling between layers with perpendicular and easy-plane magnetic anisotropies

Interlayer exchange coupling between layers with perpendicular and easy-plane magnetic anisotropies separated by a non-magnetic spacer is studied using ferromagnetic resonance. The samples consist of a Co/Ni multilayer with perpendicular magnetic anisotropy and a CoFeB layer with easy-plane anisotropy separated by a variable thickness Ru layer. At a fixed frequency, we show that there is an avoided crossing of layer ferromagnetic resonance modes providing direct evidence for interlayer coupling. The mode dispersions for different Ru thicknesses are fit to a Heisenberg-type model to determine the interlayer exchange coupling strength and layer properties. The resulting interlayer exchange coupling varies continuously from antiferromagnetic to ferromagnetic as a function of the Ru interlayer thickness. These results show that the magnetic layer single domain ground state consists of magnetizations that can be significantly canted with respect to the layer planes and the canting can be tuned by varying the Ru thickness and the layer magnetic characteristics, a capability of interest for applications in spin-transfer torque devices.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2020

Specific features of fluorescence transfer in multiply scattering randomly inhomogeneous layers under intense laser pumping

Based on the analysis of experimental data on the effect of the pulsed laser pump intensity on the spectral properties and the size of the fluorescent response zone in randomly inhomogeneous fluorescent layers, we found that the amplification of spontaneous and stimulated emission significantly affects the statistical properties of the propagation lengths of the fluorescent field partial components in the layers. The experiments are performed with layers of SiO{sub 2} and TiO{sub 2} nanoparticles saturated with rhodamine 6G, pumped by 532-nm laser radiation in the intensity range corresponding to the transient regime from excitation of spontaneous fluorescence to random lasing in the layer. The experimental data are compared with the results of statistical modelling of fluorescence transfer. It is shown that, even at a pump intensity below the random lasing threshold, the spontaneous emission amplification in a layer leads to a significant increase in the contributions to the fluorescence response from partial components with propagation lengths much larger than the layer thickness. This can be interpreted as a manifestation of the quasi-waveguide effect, in which the probability of propagation of diffuse fluorescence components along the layer over distances many times greater than its thickness and the size of the pumped region increases significantly with a decrease in the characteristic radiation amplification length in the layer. (paper)

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2013

ANGULAR MOMENTUM TRANSPORT BY ACOUSTIC MODES GENERATED IN THE BOUNDARY LAYER. I. HYDRODYNAMICAL THEORY AND SIMULATIONS

The nature of angular momentum transport in the boundary layers of accretion disks has been one of the central and long-standing issues of accretion disk theory. In this work we demonstrate that acoustic waves excited by supersonic shear in the boundary layer serve as an efficient mechanism of mass, momentum, and energy transport at the interface between the disk and the accreting object. We develop the theory of angular momentum transport by acoustic modes in the boundary layer, and support our findings with three-dimensional hydrodynamical simulations, using an isothermal equation of state. Our first major result is the identification of three types of global modes in the boundary layer. We derive dispersion relations for each of these modes that accurately capture the pattern speeds observed in simulations to within a few percent. Second, we show that angular momentum transport in the boundary layer is intrinsically nonlocal, and is driven by radiation of angular momentum away from the boundary layer into both the star and the disk. The picture of angular momentum transport in the boundary layer by waves that can travel large distances before dissipating and redistributing angular momentum and energy to the disk and star is incompatible with the conventional notion of local transport by turbulent stresses. Our results have important implications for semianalytical models that describe the spectral emission from boundary layers.

79 ASTRONOMY AND ASTROPHYSICS↗