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A molecular shift register memory at the molecular level is described. The memory elements consist of molecules can exit in either an oxidized or reduced state and the bits are shifted between the cells with photoinduced electron transfer reactions.
Molecular biology research and training program, ultrastructure and electron microscopy
In this study of molecular dissociation produced by electron impact, diatomic systems and polyatomic molecules are considered, and attention is given to the effects of thermal motion and of momentum transfer in the collision process. A procedure is described which makes it possible to 'construct' both the laboratory angular distribution and velocity distribution of the atomic fragments (or, alternatively, the time-of-flight distribution). The calculation assumes that s-wave electron scattering predominates, i.e., that excitation occurs near threshold. The computational procedure may also be reversed to allow construction of possible molecular models to fit given experimental angular and velocity distribution data.
Vacuum ultraviolet multiplets of C I, C II, and O I were produced by electron impact of CO2. Absolute emission cross sections for these multiplets were measured from threshold to 350 eV. The electrostatically focussed electron gun used in this series of experiments is described in detail. The atomic multiplets which were produced by dissociative excitation of CO2 and the cross sections at 100 eV are given. The dependence of the excitation functions on electron energy shows that these multiplets are produced by electric-dipole-allowed transitions in CO2.
Vacuum ultraviolet multiplets of C I, C II, and O I were produced by electron impact on CO2. Absolute emission cross sections for these multiplets were measured from threshold to 350 eV. The electrostatically focused electron gun used is described in detail. The atomic multiplets which were produced by dissociative excitation of CO2 and the cross sections at 100 eV are presented. The dependence of the excitation functions on electron energy shows that these multiplets are produced by electric-dipole-allowed transitions in CO2.
Electron impact cross sections for diatomic molecule ionization and excitation from modified Gryzinski theory, discussing results from molecular models
Using an electron-beam - molecular-beam apparatus and employing the relative flow technique, ratios of the differential elastic scattering cross sections (DCSs of H2 to He were measured at incident electron energies of 15-100 eV and over the angular range of 10-125 degrees. From these ratios, the absolute elastic DCSs for H2 were determined by normalization to accurate, available elastic DCSs of He. Since pure rotational structure was not resolved in this work, the DCSs reported are the sum of elastic and rotational excitations of H2 at room temperature. The reliability of the relative flow normalization to He was checked at each energy and angle by performing similar elastic DCS measurements on Ne (for which the cross sections are known). The resulting absolute Ne DCSs were found to be in good agreement (within 10 percent with the Ne elastic DCSs measured previously (Register and Trajmar, 1984). From the DCSs, integral and momentumtransfer cross sections were calculated. The present results are compared with other recent measurements.
Low-energy electrons detected with high resolution and sensitivity by their collisions with certain molecules. In thermal-electron-detection application, ambient plasma swept into collision chamber. Chamber designed to reduce stray electric fields to negligible levels and prevent inelastic and superelastic collisions with walls of collision-chamber repeller element. Instrument based on molecular detection performs high-resolution threshold photoelectron spectroscopy. Also used to detect fluorocarbons and chlorocarbons in upper atmosphere by their interaction with thermal electrons.
Atomic-nitrogen multiplets have been excited. The excitation cross sections have been measured over the energy range from threshold to 350 eV. The transition arrays, mean wavelengths, and cross sections for dissociative excitation of the multiplets at 100 eV are presented. The experiment featured a monoenergetic electron beam which was incident on a quasi-static gas target. Vacuum-ultraviolet emission features were isolated by a normal-incidence monochromator, and multiscaling pulse-counting techniques were used.
Production of core-excited autoionizing states of neutral Li having configurations of the form 1snln(prime)l(prime) has been observed over the impact-energy range from 10-50 keV. Although the results for production of all such states is remarkably consistent with a quasi-molecular-excitation model proposed by Stolterfoht and Leithaeuser (1976), production of individual lines in the observed spectra exhibits collision-velocity dependencies indicative of considerably more complex processes, including processes which appear to be inherently two-electron in nature. Excitation functions are presented for (1s2s/2/)/2/S, 1s(2s2p/3/P)/2/P, 1s(2s2p/1/P)/2/P, and (1s2p/2/)/2/D core-excited state of Li and for total core excitation.
Molecular oxygen dissociative excitation in vacuum UV by electron impact, discussing resonance triplet atomic emission cross section
Abstract missing.
A pulsed electron beam was employed in the experiment to excite a diffuse gas of hydrogen molecules. The energy resolution of the electron gun permitted careful measurements of the thresholds for the production of slow and fast H(2s) atoms. The experiment was conducted in a vacuum system that facilitated a systematic study of the angular distribution of the fragments in the dissociative excitation process. The results permit the identification of the several excited states that are involved in the production of the H(2s) fragments.
Low-energy electron-impact excitation cross sections of N2 and CO are calculated using the Schwinger multichannel formulation, and calculations are extended to the important threshold region where experimental measurement becomes difficult. Cross sections are used to determine the excitation rate coefficients for the production of the important radiative states of N2 at a variety of electronic, rotational, and vibrational temperatures. Excitation of these states requires at least 6.2 eV, and the rate coefficients increase with the electronic temperature. The dependence on the vibrational temperature is mainly determined by the shape of the potential function for the vibrational motion. A strong resonance feature near threshold is found for the excitation of CO, in agreement with previous measurements.
Integrated research and training in space molecular biology - electron microscope laboratory completion and correlated research with electron diffraction
Transition metal coordination complexes possess unique electronic structures that should be a good model for studying electronic transport behavior at a molecular level. The discrete, multiple redox states, low redox potential and the superb ability to establish contact with other molecular and electronic components by coordination chemistry have made this a subject of investigation for their possible application as active electronic components in molecular devices. We present the synthesis and electrochemical characterization of 4'-thioacetylphenyl-2'2:6',2"-terpyridine iron(II) complex and compare it with a model bis-terpyridine iron(II) complex by cyclic voltammetry. With the use of different working electrodes, the behavior of these complexes show different electron transfer rates.
An electronic shift-register memory at the molecular level is described. The memory elements are based on a chain of electron-transfer molecules and the information is shifted by photoinduced electron-transfer reactions. This device integrates designed electronic molecules onto a very large scale integrated (silicon microelectronic) substrate, providing an example of a 'molecular electronic device' that could actually be made. The design requirements for such a device and possible synthetic strategies are discussed. Devices along these lines should have lower energy usage and enhanced storage density.
An experiment, using 100-keV electrons and 10 to the 9th -rad doses, was conducted on Ultem polyetherimide film. Mechanical, electron paramagnetic resonance, and infrared spectroscopic data suggested that the radiation produced crosslinking and embrittlement of the material.