On the trapping level disposition in cadmium sulfide.
Electron trapping level disposition in CdS energy band gap indicating single energy scheme
Faeth, P. A.↗
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Magnetic-sublevel cross sections for excitation of the n 1P levels of helium by electron impact
First-order many-body theory has been used to calculate collision-frame magnetic-sublevel differential cross sections for electron-impact excitation of the n 1P (n = 2,3,4,5,6) levels of helium for electrons with incident energy in the 25-500-eV range. By combining results from electron-impact differential-cross-section measurements and electron-photon coincidence measurements, experimental magnetic-sublevel cross sections have also been derived for the excitation of the 2 1P and 3 1P levels. The theory predicts a pronounced minimum for the M = 0 magnetic-sublevel differential cross section for incident electron energies around 30 eV. The theoretical results are compared to the experimental data and some other theoretical results.
Csanak, George↗
Time domain reflectometry in time variant plasmas
The effects of time-dependent electron density fluctuations on a synthesized time domain reflectometry response of a one-dimensional cold plasma sheath are considered. Numerical solutions of the Helmholtz wave equation, which describes the electric field of a normally incident plane wave in a specified static electron density profile, are used. A study of the effects of Doppler shifts resulting from moving density fluctuations in the electron density profile of the sheath is included. Varying electron density levels corrupt time domain and distance measurements. Reducing or modulating the electron density levels of a given electron density profile affects the time domain response of a plasma and results in motion of the turning point, and the effective motion has a significant effect on measuring electron density locations.
Scherner, Michael J.↗
Confidence Level Based Approach to Total Dose Specification for Spacecraft Electronics
A confidence level based approach to total dose radiation hardness assurance is presented for spacecraft electronics. It is applicable to both ionizing and displacement damage dose. Results are compared to the traditional approach that uses radiation design margin and advantages of the new approach are discussed.
Total Dose Distributions in Space↗
Computational studies of metal-metal and metal-ligand interactions
Accurate calculations on the bond length, dipole moment, and harmonic frequency of CO are presented, using large basis sets and high levels of electron correlation. The geometric structure, force constants and binding energies of Cr(C0)6 and Cr(CO)5 are computed using large basis sets and high levels of electron correlation. The molecule 04(+) is studied, using large basis sets and high levels of electron correlation, including the CASSCF, CASSI and CASPT2 methods. Binding energies, geometries and frequencies are computed. Symmetry breaking is a particular problem for the antisymmetric stretch, which is addressed using the CASSI method. The symmetry breaking problem in 04(+) has also been studied using the Brueckner coupled cluster method. This gives results in good agreement with CASSI. A multi-region numerical integration scheme is investigated for use in Density Functional Calculations. This scheme is found to give comparable results to a widely used scheme based on the Euler-Maclaurin technique.
Barnes, Leslie A.↗
Computational studies of metal-metal and metal-ligand interactions
Accurate calculations on the bond length, dipole moment, and harmonic frequency of CO are presented, using large basis sets and high levels of electron correlation. The geometric structure, force constants and binding energies of Cr(CO)6 and Cr(CO)5 are computed using large basis sets and high levels of electron correlation. The molecule O4(+) is studied, using large basis sets and high levels of electron correlation, including the CASSCF, CASSI,and CASPT2 methods. Binding energies, geometries and frequencies are computed. Symmetry breaking is a particular problem for the antisymmetric stretch, which is addressed using the CASSI method. The symmetry breaking problem in O4(+) has also been studied using the Brueckner coupled-cluster method. This gives results in good agreement with CASSI. A multi-region numerical integration scheme is investigated for use in Density Functional Calculations. This scheme is found to give comparable results to a widely used scheme based on the Euler-Maclaurin technique.
Barnes, Leslie A.↗
Gas pressure and electron density at the level of the active zone of hollow cathode arc discharges
A model for the longitudinal variations of the partial pressures of electrons, ions, and neutral particles is proposed as a result of an experimental study of pressure variations at the level of the active zone as a function of the various discharge parameters of a hollow cathode arc. The cathode region where the temperature passes through its maximum is called active zone. The proposed model embodies the very important variations which the partial electron and neutral particles pressures undergo at the level of the active zone.
Minoo, M. H.↗
ERTS/Nimbus radiation environment information
The results of the ERTS/Nimbus satellite investigation of electron flux levels are presented. Flux calculations were made with the use of two electron environment models, both of which are static and describe the environment during the solar maximum conditions of October 1967. It is concluded that the construction of these models makes it possible to infer a change of the average quiet time electron flux levels as a function of the solar cycle.
Stassinopoulos, E. G.↗
Electronic checklists - Evaluation of two levels of automation
Two versions of an electronic checklist have been implemented in the Advanced Concepts Flight Simulator (ACFS) at NASA Research Center. The two designs differ in the degree of pilot involvement in conducting the checklists. One version (manual-sensed), requires the crew to manually acknowledge the completion of each checklist item. The other version (automatic-sensed), automatically indicates completed items without requiring pilot acknowledgement. These two designs and a paper checklist (as a control condition) were evaluated in line oriented simulation. Twelve aircrews from one major air-carrier flew a routine, four leg, short-haul trip. This paper presents and discusses the portion of the experiment that was concerned with measuring the effect of the degree of automation on the crews' performance. It discusses and presents evidence for a potential down-side of implementing an electronic checklist that is designed to provide fully redundant monitoring of human procedure execution and monitoring.
Palmer, Everett↗
Glauber theory of atomic-hydrogen excitation by electron impact
Hydrogen atom excitation at various energy levels by electron impact, applying Glauber theory
Bassel, R. H.↗
Polarizabilities of two-electron positive ions and Rydberg levels of lithium
Second-order sums are computed for the two-electron positive ions Li(+), Be(2+), and B(3+) by representing the intermediate states as discrete pseudostates. The Hamiltonian for the system is given and translated to semi-Jacobi variables for its derivation in reduced Rydberg units. The interaction potential is developed in its multipole form and employed in second-order perturbation theory. The perturbation is always a multipole-potential term, and the initial and intermediate states are constructed from two-particle Hylleraas basis sets. The resulting pseudostates are shown to represent the continuum with good convergence, and the asymptotic-optical-potential method is applied to the two-body quantities to determine the energy levels of three-electron systems in high Rydberg states. The method is shown to give accurate values for the polarizabilities of the two-electron isoelectronic systems.
Bhatia, A. K.↗
Temperature coefficients for concentrator cells at various electron and proton fluence levels
Data are presented on the Isc, Voc and Pmax temperature coefficients for several small concentrator solar cells. The cells are AlGaAs (1.72 eV), GaAs, silicon and InGaAs (1.1 eV) concentrator cells operating at 6.25 and 100 times AM0. The temperature range covered was 25 to 100 C. Cells were irradiated with 1-MeV electrons and 37-MeV protons, and data are presented at different fluence levels.
Curtis, Henry B.↗
Theoretical study of the bonding of Sc, Y, and La singly charged and dipositive ions to C2H2, C2H4, and C3H6
The interaction of the Sc and Y singly-charged and dipositive ions with C2H2, C2H4, and C3H6 is studied using electronic structure calculations that include high levels of electron correlation. These results are compared with comparable calculations performed previously for La(+) and La(2+). For C2H2 and C2H4, all three metal ions insert into the C-C pi bond, making a three-membered ring. The optimal structures for the MC3H6(+) ions all involve rearrangement to make a four-membered ring. The strength of the metal-ligand bond for the singly charged ions follows the order La greater than Sc equal to about Y. In contrast, the bonds involving the dipositive ions are electrostatic, so that the binding energy increases as the size of the ion decreases, leading to the trend Sc greater than Y greater than La.
Bauschlicher, Charles W., Jr.↗
Theoretical study of the bonding of Nb(2+) to CH2, C2H2, and C2H4
The bonding of Nb(2+) with CH2, C2H2, and C2H4 is studied by using electronic structure calculations that include high levels of electron correlation. The binding energy for NbCH2(2+) is in good agreement with the lower bound determined from the reaction with CH4 but is significantly smaller than the value determined from the binding energy and ionization potential of NbCH2(+). The calculations and a new interpretation of the experiment indicate that the larger value is in error primarily because the ionization potential of NbCH2(+) determined from bracketing charge-exchange reactions is too small. The computed binding energy of NbC2H2(2+) is in good agreement with experiment. The calculations show that the bonding is predominantly covalent in character for both NbCH2(2+) and NbC2H2(2+), whereas for NbC2H4(2+) the electronic states that are predominantly ionic and covalent are nearly degenerate. The trend in binding energies, CH2 greater than C2H2 greater than C2H4, is consistent with the energy required to prepare the ligands for bonding.
Bauschlicher, Charles W., Jr.↗
Electron Impact Excitation of Autoionizing Levels of Kr and Xe Between the (sup 2)P(sub 3/2) and (sup 2)P(sub 1/2) Ionic Limits
We have observed electrons ejected from autoionizing levels which lie between the (sup 2)P(sub 3/2) and (sup 2)P(sub 1/2) ionic limits for Kr and Xe. Kinetic energy spectra of the ejected electrons were obtained following electron impact excitation of the target gases by using time-of-flight spectroscopy in a crossed beam experiment. Spectral features which correspond to electrons ejected from both odd and even parity autoionizing levels have been identified.
autoionizing ejected electrons↗
A study of electron transfer using a three-level system coupled to an ohmic bath
Electron transfer is studied using a multi-level system coupled to a bosonic bath. Two body correlation functions are obtained using both exact enumeration of spin paths and Monte Carlo simulation. It was found that the phase boundary for the coherent-incoherent transition lies at a smaller friction in the asymmetric two-level model than in the symmetric two-level model. A similar coherent-incoherent transition is observed for three-level system.
Takasu, Masako↗
High resolution threshold photoelectron spectroscopy by electron attachment
A system is provided for determining the stable energy levels of a species ion, of an atomic, molecular, or radical type, by application of ionizing energy of a predetermined level, such as through photoionization. The system adds a trapping gas to the gaseous species to provide a technique for detection of the energy levels. The electrons emitted from ionized species are captured by the trapping gas, only if the electrons have substantially zero kinetic energy. If the electrons have nearly zero energy, they are absorbed by the trapping gas to produce negative ions of the trapping gas that can be detected by a mass spectrometer. The applied energies (i.e. light frequencies) at which large quantities of trapping gas ions are detected, are the stable energy levels of the positive ion of the species. SF6 and CFCl3 have the narrowest acceptance bands, so that when they are used as the trapping gas, they bind electrons only when the electrons have very close to zero kinetic energy.
Chutjian, A.↗
Problem of electron contamination
Data are presented from two experiments to demonstrate the effect of electron contamination on X-ray measurements within the magnetosphere. The data are taken from a rocket flight which detected auroral X-rays in the energy range from 2 to 10 keV and from Uhuru measurements of the magnetic field-modulated electron flux. It is shown that the level of electron contamination rendered the rocket observations completely unreliable, but profiles of the charged particle flux as functions of terrestrial longitude were able to be obtained from the Uhuru data. It is stressed that particle contamination of X-ray data will occur even near the equator at high electron threshold energy. Corrective measures are proposed to eliminate the contamination or to reduce or evaluate the effects of such contamination.
Garmire, G.↗