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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
NASA NTRS1986

Theoretical Electric Dipole Moments of SiH, GeH and SnH

Accurate theoretical dipole moments (mu(sub c) have been computed for the X(exp 2)Pi ground states of Si(-)H(+)(0.118 D), Ge(+)H(-)(0.085 D) and Sn(+)H(-)(0.357 D). The trend down the periodic table is regular and follows that expected from the electronegativities of the group IV atoms. The dipole moment of 1.24 +/- 0.1 D for GeH recently derived by Brown, Evenson and Sears from the relative intensities of electric and magnetic dipole transitions in the 10 microns spectrum of the X(exp 2)Pi state is seriously questioned.

Pettersson, Lars G. M.↗
NASA NTRS1986

Theoretical Electric Dipole Moments and Dissociation Energies for the Ground States of GaH-BrH

Reliable experimental diople moments are available for the ground states of SeH and BrH whereas no values have been reported for GaH and AsH a recently reported experimental dipole moment for GeH of 1.24 + or -0.01 D has been seriously questioned, and a much lower value of, 0.1 + or - 0.05 D, suggested. In this work, we report accurate theoretical dipole moments, dipole derivatives, dissociation energies, and spectroscopic constants (tau(sub e), omega(sub e)) for the ground states of GaH through BrH.

Pettersson, Lars G. M.↗
NASA NTRS1986

Theoretical Study of the Electric Dipole Moment Function of the CIO Molecule

The potential energy function and electric dipole moment function (EDMF) are computed for CIO Chi(sup 2)Pi using several different techniques to include electron correlation. The EDMF is used to compute Einstein coefficients, vibrational lifetimes, and dipole moments in higher vibrational levels. Remaining questions concerning the position of the maximum of the EDMF may be resolved through experimental measurement of dipole moments of higher vibrational levels. The band strength of the 1-0 fundamental transition is computed to be 12 +/- 2 /sq cm atm in good agreement with three experimental values, but larger than a recent value of 5 /sq cm atm determined from infrared heterodyne spectroscopy. The theoretical methods used include SCF, CASSCF, multireference singles plus doubles configuration interaction (MRCI) and contracted CI, coupled pair functional (CPF), and a modified version of the CPF method. The results obtained using the different methods are critically compared.

Pettersson, Lars G. M.↗
NASA NTRS1997

Remote Sensing of Dipole Rings

Historical satellite-derived sea surface temperature (SST) data are reanalyzed with a zebra color palette and a thermal separatrix method. The new results from this reanalysis are as follows: (a) Thirteen observational sequences of six rings from the Gulf Stream and the Brazil Current, which have historically been interpreted as solitary vortices or monopoles are shown to have a dipolar character; (b) some of these dipole rings have been observed in the open ocean, thereby eliminating the possibility that they are sustained by topographic interactions with the continental slope; (c) whether interacting with other features or evolving as isolated circulations, dipoles are seen to rotate within a relatively narrow range of approximately 4-8 deg/day (interacting) and 10-11 deg/day (isolated); and (d) feature tracking delineates energetic fluid in both vortices and eliminates the possibility of interpreting dipole rings as transient features produced by active monopoles and patches of entrained fluid.

Hooker, Stanford B.↗
NASA NTRS2004

Modified Coulomb-Dipole Theory for 2e Photoionization

In the light of recent experiment on 2e photoionization of Li near threshold, we have considered a modification of the Coulomb-dipole theory, retaining the basic assumption that the threshold is dominated by asymmetric events in phase space [implies r(sub 1), k(sub 1)) greater than or equal to 2(r(sub 2), k(sub )]. In this region [in a collinear model, 2/r(sub 12) approached + 2/(r(sub 1)+r(sub 2)] the interaction reduces to V(rIsub 1) is greater than or equal to 2r(sub 2) is identically equal to [(-Z/r(sub 2)-(A-1)/r(sub 1)] + [(-2r(sub 2)/r(sub 1 exp 2)] is identically equal to V(sub c)+[V(sub d)]. For two electron emission Z = 2, thus both electrons see a Coulomb potential (V(sub c)) asymptotically, albeit each seeing a different charge. The residual potential (V(sub d)) is dipole in character. Writing the total psi = psi (sub c) + psi(sub d) = delta psi, and noting that. (T+V(sub c)-E)psy(sub c) = 0 and (T+V(sub c))psi(sub d) = 0 can be solved exactly, we find, substituting psi into the complete Schrod. Eq., that delta psi = -(H-E)(exp -1)(V(sub d) psi(sub 0)+V(sub c psi (sub 1). Using the fact that the absolute value of V(sub c) is much more than the absolute value of V(sub d) in almost all of configuration space, we can replace H by H(sub 0) in 9H-E)(exp -1) to obtain an improved approximation psi (improved) = psi(sub c) + psi(sub d) -(H(sub 0)-E)(exp -1) (V(sub c) psi (sub 0) + V(sub c) psi(sub 1). Here's the Green's function (H(sub 0)-E)(exp -1), can be exhibited explicitly, but the last term in psi (improved) is small, compared to the first two terms. Inserting them into the transition matrix element, which one handles in the usual way, we obtain in the limit E approaches 0, the threshold law: Q(E) alpha E + M(E)E(exp 5/4) + higher order (Eq. 1a). The modulation function, M(E), is a well-defined (but very non-trivial integral, but it is expected to be well approximated by a sinusoidal function containing a dipole phase term (M(E) = c sin[alpha log (E) + micron] (Eq. 1b). Experimental results show definite modulations, and are well fitted by Eqs (1).

Source record↗
NASA NTRS2022

Wide-band Planar Dipole Antennas for Earth and Planetary Science Applications

Dipole antennas are well known and are used for a variety of applications in many different shapes and forms. Wide-band planar dipole antennas, in particular, have been developed, designed and implemented in the past and have shown promising RF performance. In this paper, we describe a particular style of a wide-band planar dipole antenna that is being developed over a wide range of frequencies for a variety of scientific applications on Earth, the Moon and beyond. Aside from the appealing RF performance, this antenna element also lends itself to being easily folded and stowed on a small satellite and deployed once in space, making it very useful in applications where large apertures or low frequency/long wavelength antennas need to be deployed from a small platform (compared to the wavelength).

Shenoy, Tushar↗
DOE OSTI2019

Permanent Magnet Dipole-Quadrupole and Correcto-Tuner for Small Bore Accelerators

Electromagnets are used to bend electron beams and generate X-ray light. Permanent magnets have many advantages over electromagnets and are being studied as an alternative for small bore accelerators. This paper focuses on the mechanical design of two holders. First, a holder for the corrector and tuner permanent magnet assembly, which aims to correct the errors in the permanent magnetic field strength and orientation. Second, a holder for the dipole-quadrupole magnet assembly, which aims to provide the required magnetic strength to steer the electrons. Prototypes for the corrector, tuner and dipole-quadrupole holders were designed and tested to validate conceptual design. Results show that the corrector magnets can be oriented into a prescribed configuration, the tuner magnets can be oriented simultaneously regardless of the magnetic forces involved, and the dipole-quadrupole magnets can provide the magnetic strength required to steer electrons.

Huschke, Christopher↗
DOE OSTI2016

On the effects on a Landau-type system for an atom with no permanent electric dipole moment due to a Coulomb-type potential

We analyse the bound states for a Landau-type system for an atom with no permanent electric dipole moment subject to a Coulomb-type potential. By comparing the energy levels for bound states of the system with the Landau quantization for an atom with no permanent electric dipole moment (Furtado et al., 2006), we show that the energy levels of the Landau-type system are modified, where the degeneracy of the energy levels is broken. Another quantum effect investigated is a dependence of the angular frequency of the system on the quantum numbers associated with the radial modes and the angular momentum. As examples, we obtain the angular frequency and the energy levels associated with the ground state and the first excited state of the system.

74 ATOMIC AND MOLECULAR PHYSICS↗
DOE OSTI2015

Nuclear Magnetic Dipole and Electric Quadrupole Moments: Their Measurement and Tabulation as Accessible Data

The most recent tabulations of nuclear magnetic dipole and electric quadrupole moments have been prepared and published by the Nuclear Data Section of the IAEA, Vienna [N. J. Stone, Report No. INDC(NDS)-0650 (2013); Report No. INDC(NDS)-0658 (2014)]. The first of these is a table of recommended quadrupole moments for all isotopes in which all experimental results are made consistent with a limited number of adopted standards for each element; the second is a combined listing of all measurements of both moments. Both tables cover all isotopes and energy levels. In this paper, the considerations relevant to the preparation of both tables are described, together with observations as to the importance and (where appropriate) application of necessary corrections to achieve the “best” values. Some discussion of experimental methods is included with emphasis on their precision. The aim of the published quadrupole moment table is to provide a standard reference in which the value given for each moment is the best available and for which full provenance is given. A table of recommended magnetic dipole moments is in preparation, with the same objective in view.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Experimental study of electric dipoles on an oxygen-adsorbed Si(100)-2 × 1 surface by non-contact scanning nonlinear dielectric microscopy

Oxygen-adsorption on a Si(100)-2 × 1 surface is investigated by using non-contact scanning nonlinear dielectric microscopy (NC-SNDM). On the Si(100)-2 × 1 surface exposed to oxygen (O{sub 2}) gas at room temperature, several variations in atomic configuration and electric dipole moment of dimers are observed. Models are proposed for oxygen adsorption which are consistent with the topographies and electric dipole moment distributions obtained by NC-SNDM.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Interacting He and Ar atoms: Revised theoretical interaction potential, dipole moment, and collision-induced absorption spectra

Coupled cluster quantum chemical calculations of the potential energy surface and the induced dipole surface are reported for the He–Ar van der Waals collisional complex. Spectroscopic parameters are derived from global analytical fits while an accurate value for the long-range dipole coefficient D{sub 7} is obtained by perturbation methods. Collision-induced absorption spectra are computed quantum mechanically and compared with existing measurements.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Development of a Bi2212 Dipole Insert at Fermilab

A goal of the U.S. Magnet Development Program (US-MDP) is high-field magnets for accelerators with magnetic fields larger than 15 T, i.e., above the limits of Nb 3 Sn accelerator magnets. Composite round wires and Rutherford cables made of high temperature superconductor Bi2212 may achieve this goal. Bi2212 is sensitive to transverse stresses and strains, and this requires stress management in the coil design. A stress management approach was developed at Fermilab for high-field large-aperture Nb 3 Sn accelerator magnets. Now it is being applied to high-field dipole insert coils based on Bi2212 Rutherford cable. Here this paper describes the insert coil design and main parameters, including the superconducting wire and cable. The coil will be installed inside a 60-mm bore Nb 3 Sn dipole outsert coil and cold iron yoke. The Bi2212 coil will be tested individually and in series with the Nb 3 Sn outsert coil. The expected Bi2212 insert test parameters are reported and discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2018

Rotation of a Spherical Particle with Electrical Dipole Moment Induced by Steady Irradiation in a Static Electric Field

Rotation of a spherical particle in a static electric field and under steady irradiation that induces an electric dipole moment in the particle is studied for the first time. Along with the general treatment of the phenomenon, we analyze possible mechanisms underlying the photoinduction of dipole moment in the particle. Estimations of the angular velocity and the power expended by the rotating particle are provided. The indicated characteristics reach their maximum values if the size of particles is within the range of 10 nm to 10 μm.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

On Optical Dipole Moment and Radiative Recombination Lifetime of Excitons in WSe 2

Optical dipole moment is the key parameter of optical transitions, as it directly determines the strength of light–matter interaction such as intrinsic radiative lifetime. However, experimental determination of these fundamental properties of excitons in monolayer WSe 2 is largely limited, because the commonly used measurement, such as (time-resolved) photoluminescence, is inherently difficult to probe the intrinsic properties. For example, dark states below bright exciton can change the photoluminescence emission rate by orders of magnitude and gives an “effective” radiative lifetime distinctive from the intrinsic one. On the other hand, such “effective” radiative lifetime becomes important itself because it describes how dark states affect exciton dynamics. Unfortunately, the “effective” radiative lifetime in monolayer WSe 2 is also not determined as it requires photoluminescence measurement with resonant excitation, which is technically difficult. These difficulties are overcome here to obtain both the “intrinsic” and “effective” radiative lifetime experimentally. A framework is developed to determine the dipole moment and “intrinsic” radiative lifetime of delocalized excitons in monolayer WSe 2 from the absorption measurements. In addition, the “effective” radiative lifetime in WSe 2 is obtained through time-resolved photoluminescence and absolute quantum-yield measurement at resonant excitation. These results provide helpful information for fundamental understanding of exciton light–matter interaction in WSe 2 .

36 MATERIALS SCIENCE↗
DOE OSTI2016

Energy level shifts at the silica/Ru(0001) heterojunction driven by surface and interface dipoles

Charge redistribution at heterogeneous interfaces is a fundamental aspect of surface chemistry. Manipulating the amount of charges and the magnitude of dipole moments at the interface in a controlled way has attracted tremendous attention for its potential to modify the activity of heterogeneous catalysts in catalyst design. Two-dimensional ultrathin silica films with well-defined atomic structures have been recently synthesized and proposed as model systems for heterogeneous catalysts studies. R. Wlodarczyk et al. (Phys. Rev. B, 85, 085403 (2012)) have demonstrated that the electronic structure of silica/Ru(0001) can be reversibly tuned by changing the amount of interfacial chemisorbed oxygen. Here we carried out systematic investigations to understand the underlying mechanism through which the electronic structure at the silica/Ru(0001) interface can be tuned. As corroborated by both in situ X-ray photoelectron spectroscopy and density functional theory calculations, the observed interface energy level alignments strongly depend on the surface and interfacial charge transfer induced dipoles at the silica/Ru(0001) heterojunction. These observations may help to understand variations in catalytic performance of the model system from the viewpoint of the electronic properties at the confined space between the silica bilayer and the Ru(0001) surface. As a result, the same behavior is observed for the aluminosilicate bilayer, which has been previously proposed as a model system for zeolites.

2D zeolites↗