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Results for “Rydberg atoms”

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 19 records
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Effect of dispersion forces on squeezing with Rydberg atoms

We report exact results concerning the effect of dipole-dipole interaction (dispersion forces) on dynamic and steady-state characteristics of squeezing in the emitted fluorescent field from two identical coherently driven two-level atoms. The atomic system is subjected to three different damping baths in particular the normal vacuum, a broad band thermal field and a broad band squeezed vacuum. The atomic model is the Dicke model, hence possible experiments are most likely to agree with theory when performed on systems of Rydberg atoms making microwave transitions. The presence of dipole-dipole interaction can enhance squeezing for realizable values of the various parameters involved.

Ng, S. K.↗
NASA NTRS1986

Double photon excitation of high-Rydberg atoms as a long-lived submillimeter detector

A method and apparatus for detecting submillimeter or IR radiation is disclosed. A rare gas, such as xenon, is supplied at its ground state via a pressurized cylinder and an adjustable leak valve into a cryogenically cooled detection area. The ground state of xenon is double photon excited to a particularized level of the Rydberg series by a resonance lamp and a laser. The doubly excited gas is then further excited by the radiation to be measured. A field ionization and an ion measurement indicative of the radiation intensity is achieved.

Chutjian, A. N.↗
NASA NTRS1977

Dissociative excitation of H2, HD, and D2 by electron impact

Time-of-flight techniques have been used to investigate the electron-impact dissociation of H2, HD, and D2 in order to determine the effect of isotopic mass variation in the target molecule on the dissociative excitation process. At incident electron energies near 100 eV, the time-of-flight spectrum produced from each molecule consists of atoms in the metastable 2s state and in high-lying long-lived Rydberg levels. The individual time-of-flight distributions, kinetic-energy spectra, and relative differential cross sections for these two species resulting from each molecule have been measured. The kinetic-energy spectrum of the Rydberg atoms produced from dissociative excitation of H2 was notably dissimilar in shape from the corresponding distributions produced from HD and D2. Also the 2s and Rydberg production cross sections differed between the three molecules. In the dissociation of the heteronuclear HD molecule, the ratio of fast H(2s) atoms to D(2s) atoms was about 1 to 1, while the same ratio comparing the Rydberg atoms was nearly 2 to 1. These differences indicate the influence of the mass variation on the position of the Franck-Condon region in the production of 2s atoms and on the competition between autoionization and dissociation in the formation of Rydberg fragments.

Carnahan, B. L.↗
NASA NTRS1983

Low energy electron magnetometer using a monoenergetic electron beam

A low energy electron beam magnetometer utilizes near-monoenergetic electrons thereby reducing errors due to electron energy spread and electron nonuniform angular distribution. In a first embodiment, atoms in an atomic beam of an inert gas are excited to a Rydberg state and then electrons of near zero energy are detached from the Rydberg atoms. The near zero energy electrons are then accelerated by an electric field V(acc) to form the electron beam. In a second embodiment, a filament emits electrons into an electrostatic analyzer which selects electrons at a predetermined energy level within a very narrow range. These selected electrons make up the electron beam that is subjected to the magnetic field being measured.

Singh, J. J.↗
NASA NTRS1995

Microgravity and Charge Transfer in the Neuronal Membrane: Implications for Computational Neurobiology

Evidence from natural and artificial membranes indicates that the neural membrane is a liquid crystal. A liquid-to-gel phase transition caused by the application of superposed electromagnetic fields to the outer membrane surface releases spin-correlated electron pairs which propagate through a charge transfer complex. The propagation generates Rydberg atoms in the lipid bilayer lattice. In the present model, charge density configurations in promoted orbitals interact as cellular automata and perform computations in Hilbert space. Due to the small binding energies of promoted orbitals, their automata are highly sensitive to microgravitational perturbations. It is proposed that spacetime is classical on the Rydberg scale, but formed of contiguous moving segments, each of which displays topological equivalence. This stochasticity is reflected in randomized Riemannian tensor values. Spacetime segments interact with charge automata as components of a computational process. At the termination of the algorithm, an orbital of high probability density is embedded in a more stabilized microscopic spacetime. This state permits the opening of an ion channel and the conversion of a quantum algorithm into a macroscopic frequency code.

Wallace, Ron↗
NASA NTRS1994

Supersymmetry and radial squeezed states for Rydberg wave packets

Atomic supersymmetry provides an analytical effective-potential model useful for describing certain aspects of Rydberg atoms. Experiments have recently demonstrated the existence of Rydberg wave packets localized in the radial coordinated with p-state angular distribution. This paper shows how atomic supersymmetry can be used to treat radial Rydberg wave packets via a particular analytical type of squeezed state, called a radial squeezed state.

Bluhm, Robert↗
NASA NTRS1974

Partially autoionizing states of atomic oxygen

Certain Rydberg states and an intershell transition of atomic oxygen were shown to partially autoionize, and to produce emission spectra competitive with autoionization. These states are forbidden to autoionize on the basis of LS coupling; but they were observed both in emission spectroscopy and in photoelectron spectroscopy. The results explain an unidentified structure in the 584 Angstrom He I atomic O spectrum observed by previous investigators.

Samson, J. A. R.↗
NASA NTRS1980

Effect of blackbody radiation on the threshold for two-electron photodetachment of H/-/

The threshold law of the titled process, which is of the same form as that for electron-impact ionization of H, can experimentally be contaminated by simultaneous single photodetachment and Rydberg excitation of the residual atom, followed by ionization of the Rydberg atom by (room-temperature) blackbody photons. This gives a signal indistinguishable from direct double photodetachment. The correction is here calculated and shown to be finite at the double photodetachment threshold, and to have, possibly, an implication about the form of the threshold law itself. However, at room temperature its contribution is found to be small as it pertains to a recently initiated experiment at the Los Alamos Meson Physics Facility for available energies greater than a millivolt above threshold. The temperature dependence of the correction is shown to be large (k/B/T) to the 7/2; thus at higher temperatures the effect may be observable.

Temkin, A.↗
NASA NTRS1987

High-Rydberg Xenon Submillimeter-Wave Detector

Proposed detector for infrared and submillimeter-wavelength radiation uses excited xenon atoms as Rydberg sensors instead of customary beams of sodium, potassium, or cesium. Chemically inert xenon easily stored in pressurized containers, whereas beams of dangerously reactive alkali metals must be generated in cumbersome, unreliable ovens. Xenon-based detector potential for infrared astronomy and for Earth-orbiter detection of terrestrial radiation sources. Xenon atoms excited to high energy states in two stages. Doubly excited atoms sensitive to photons in submillimeter wavelength range, further excited by these photons, then ionized and counted.

Chutjian, Ara↗
NASA NTRS1972

Partially autoionizing states of atomic oxygen

The Rydberg states 3d' (3Po)2,1,0 and 3s'' (3Po)2,1,0 and the inner shell transition 2s 2p5 (3Po)2,1,0, which are forbidden to autoionize on the basis of LS coupling, were observed in emission spectroscopy and in autoionization spectra produced in the photoelectron spectrum of atomic oxygen.

Samson, J. A. R.↗
NASA NTRS1980

Need for high resolution in VUV Rydberg state spectroscopy

The paper emphasizes the necessity of high energy resolution (resolving powers greater than 100,000) in VUV spectroscopic determinations of atomic and molecular Rydberg electronic structures. Attention is given to spectral observations of Rydberg levels in Ge I near the 4p 2P(0)1/2 limit, in Sr I near the 4d 2D3/2 limit, and in diatomic hydrogen halides (especially H I) below the X2Pi3/2 limit.

Ginter, M. L.↗
NASA NTRS1975

Dissociation of CH4 and CD4 by electron impact - Production of metastable and high-Rydberg hydrogen and carbon fragments

Production of hydrogen and carbon atoms in metastable and high-lying Rydberg states by electron-impact dissociation of methane and deuterated methane is investigated for incident electron energies ranging from threshold values to 300 eV. Threshold energies for five different processes resulting in metastable hydrogen and carbon atoms are determined in the energy range from 20 to 70 eV, and it is shown that metastable hydrogen atoms are produced in four of these collisional processes while metastable carbon atoms are produced in the other. The nature of each collisional process is described, differential cross sections are derived for the dissociative excitation of both types of atoms to metastable and high-Rydberg states at 100 eV, and the onset energy for UV photon production is measured. Much of the data is interpreted in terms of the ion core model suggested by Kupriyanov (1968) and developed by Freund (1971).

Finn, T. G.↗
NASA NTRS1975

Fast metastable fragments produced by dissociative excitation of carbonyl sulfide

Dissociative excitation of OCS by electron impact has been studied using the method of translational spectroscopy. Time-of-flight distributions and excitation functions of the fast metastable fragments have been measured. The results are compared with similar measurements on CO2 and show that a variety of metastable fragments including CO(a 3Pi), S(5S), O(5S) as well as long-lived high-lying atomic and molecular Rydberg fragments can contribute to dissociation.

Van Brunt, R. J.↗
NASA NTRS2001

Polarizabilities and Other Properties of the td Muons Molecular Ion

Wavefunctions of Hylleraas type were used earlier to calculate energy levels of muonic systems. Recently, we found in the case of the molecular ions H2+, D2+ and HD+ that it was necessary to include high powers of the internuclear distance in the Hylleraas functions to localize the nuclear motion when treating the ions as three-body systems without invoking the Born-Oppenheimer approximation. We try the same approach in a muonic system, td(mu-). Improved convergence is obtained for J = 0 and 1 states for shorter expansions when we use this type of generalized Hylleraas function, but as the expansion length increases the high powers are no longer useful. We obtain good energy values for the two lowest J = 0 and J = 1 states and compare them with the best earlier calculations. Expectation values are obtained for various operators, the Fermi contact parameters, and the permanent quadrupole moment. The cusp conditions are also calculated. The polarizability of the ground state is then calculated using second-order perturbation theory with intermediate J = 1 pseudostates. It should be possible to measure the polarizability by observing Rydberg states of atoms with td(mu-) acting as the nucleus.

Bhatia, A. K.↗
NASA NTRS2013

A Comprehensive X-Ray Absorption Model for Atomic Oxygen

An analytical formula is developed to accurately represent the photoabsorption cross section of atomic Oxygen for all energies of interest in X-ray spectral modeling. In the vicinity of the K edge, a Rydberg series expression is used to fit R-matrix results, including important orbital relaxation effects, that accurately predict the absorption oscillator strengths below threshold and merge consistently and continuously to the above-threshold cross section. Further, minor adjustments are made to the threshold energies in order to reliably align the atomic Rydberg resonances after consideration of both experimental and observed line positions. At energies far below or above the K-edge region, the formulation is based on both outer- and inner-shell direct photoionization, including significant shake-up and shake-off processes that result in photoionization-excitation and double-photoionization contributions to the total cross section. The ultimate purpose for developing a definitive model for oxygen absorption is to resolve standing discrepancies between the astronomically observed and laboratory-measured line positions, and between the inferred atomic and molecular oxygen abundances in the interstellar medium from XSTAR and SPEX spectral models.

supernova remnants↗
NASA NTRS1996

On the Use of a Mixed Gaussian/Finite-Element Basis Set for the Calculation of Rydberg States

Configuration-interaction studies are reported for the Rydberg states of the helium atom using mixed Gaussian/finite-element (GTO/FE) one particle basis sets. Standard Gaussian valence basis sets are employed, like those, used extensively in quantum chemistry calculations. It is shown that the term values for high-lying Rydberg states of the helium atom can be obtained accurately (within 1 cm -1), even for a small GTO set, by augmenting the n-particle space with configurations, where orthonormalized interpolation polynomials are singly occupied.

Thuemmel, Helmar T.↗