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  • 1
    Electronic Resource
    Electronic Resource
    Study of a laser-heated electron gun (1996)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 67 (1996), S. 4098-4102 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A method of cathode heating using a laser was studied for an electron gun. In order to observe the practicality of the heating system, the characteristics of the laser-heated gun with a dispenser and LaB6 thermionic cathodes have been experimentally investigated. The direct laser irradiation is so efficient that the gun is equipped without heat shielding, a cooling system, or an electrical circuit in the gun chamber for cathode heating. Modeling, based on the experimental data, indicates that the cathode temperature is proportional to one-fourth power of the laser power and that laser power loss and conduction loss of heat in the gun assembly are negligible. An electron beam current density 0.48 A/cm2 was measured with 26 W laser power for a dispenser cathode of 0.06 cm2 emission area. Current density 0.16 A/cm2 with 25 W was recorded for a LaB6 cathode of area 0.12 cm2. Electron beam emittance has been measured by using the typical pepper-pot technique. It was observed that the growth of electron beam emittance was very small in the laser heating. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1147577
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  • 2
    Electronic Resource
    Electronic Resource
    Satellites and double ionization continua in the CS2 photoelectron spectrum (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 2536-2548 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The CS+2 valence satellites have been studied with photoelectron spectroscopy using synchrotron radiation in the 35–75 eV photon energy range. Partial cross sections (σ) and asymmetry parameters (β) for most bands have been measured as a function of photon energy. Below 28 eV binding energy, the symmetry of satellite bands has been identified on the basis of their β value and a comparison between experimental photoelectron spectra and new ab initio SCF-CI calculations of CS+2 corrected for transition moments. For the bands with binding energies above 28 eV no configuration interactions states of CS+2 are predicted with significant intensity. We suggest that they originate from the opening of direct double ionization continua. This is supported by the similarity of their cross sections with the total double ionization one.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453093
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  • 3
    Electronic Resource
    Electronic Resource
    Experimental and theoretical study of configuration interaction states of CO+2 (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 2050-2061 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Configuration interaction states of CO+2 have been observed as satellites in a high resolution photoelectron spectrum of CO2 using an angle resolved electron spectrometer and far UV synchrotron radiation in the 30–55 eV photon energy range. Ten satellites have been identified in the 22–40 eV binding energy region and classified as the result of outer and inner valence ionization processes on the basis of their asymmetry parameter ( β) values. Theoretical calculations of configuration interaction states of CO+2 using an ab-initio SCF-CI method show that three-hole-two-particle excited configurations are necessary to explain the line positions and intensities. The calculated satellite spectrum, corrected for transition moments at 45 and 1254 eV, shows an excellent agreement with experiment and allows assignments of both outer and inner valence satellite lines, with Πg, Πu, Σ+g, and Σ+u symmetries.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450413
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  • 4
    Electronic Resource
    Electronic Resource
    Vibronic coupling and other many-body effects in the 4σ−1g photoionization channel of CO2 (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 949-956 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Vibrational branching ratios and photoelectron angular distributions were measured for 4σ−1g photoionization of CO2 in the energy range 20–28 eV. Of particular interest are three vibrational components of the resulting CO+2 C˜ 2Σ+g state—the allowed (000) and (100) bands and the forbidden (101) band. The wavelength dependence of the beta parameter for the forbidden band deviated significantly from that of the two allowed bands, showing instead a strong resemblance to that of the B˜ 2Σ+u state. This behavior suggests that vibronic coupling to the B˜ 2Σ+u state is responsible for the appearance of the forbidden (101) band in the C˜ 2Σ+g state photoelectron spectrum. We also observe evidence for other many-body effects—shape-resonance-induced continuum–continuum coupling and doubly excited autoionizing resonances—in the present data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.459985
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  • 5
    Electronic Resource
    Electronic Resource
    Autoionization dynamics in the valence-shell photoionization spectrum of CO (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 812-819 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Autoionizing Rydberg series in the valence-shell spectrum of CO have been studied by determining the high resolution relative photoionization cross section of cooled CO in the energy region 14.0–20.0 eV and by determining the vibrational branching ratios and the photoelectron angular distributions for production of CO+ X 2Σ+, v+=0–2 in the energy region 16.75–18.75 eV. Of particular interest are three prominent spectral features between 17.0 and 17.5 eV that result from interactions involving Rydberg series converging to the excited A 2Π and B 2Σ+ states of the ion. The results are discussed in the context of recent two-step multichannel quantum defect theory calculations by Leyh and Raseev (the following paper).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455204
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  • 6
    Electronic Resource
    Electronic Resource
    Vibrationally resolved shape resonant photoionization of N2O (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 90 (1989), S. 1544-1550 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We report a vibrationally resolved dispersed fluorescence study of 7σ−1 shape resonant photoionization in N2O. Previous work indicates that there are two shape resonances in the εσ channel, and our results demonstrate that the lower energy shape resonance (hνexc≈20 eV) results in non-Franck–Condon vibrational branching ratios over a wide range. Moreover, the cross section curves for alternative vibrational modes behave differently, and we show that the symmetric stretch exerts a greater influence on resonance behavior than the asymmetric stretching vibration. Such comparisons of vibrationally resolved partial cross section curves provide qualitative insights into the shape resonant photoionization dynamics for polyatomic targets. The higher energy shape resonance is apparently masked by the presence of the dominant nonresonant επ channel. In addition to information on the photoionization dynamics, these results also provide spectroscopic data on the ionic potential surfaces. Specifically, we obtain ratios of Franck–Condon factors for N2O+ (A→X) transitions which are useful for testing calculated properties of the ion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456097
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  • 7
    Electronic Resource
    Electronic Resource
    Vibrationally resolved electronic autoionization of core–hole resonances (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 4048-4053 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We investigate the dynamics of molecular core–hole decay using dispersed fluorescence from an ionic valence–hole state in N2. A core–hole excited state is created via the N2(1s→1 π*g) transition, and this state electronically autoionizes to the N+2(B 2Σ+u) state. The vibrational branching ratios for the N+2(B 2Σ+u) state are then determined from N+2(B 2Σ+u→X 2Σ+g) fluorescence. Fundamental aspects of core–hole state decay emerge clearly from these measurements. In particular, interference effects due to lifetime broadening of vibrational levels of the core–hole state can be investigated quantitatively using this method. As a result, dispersed fluorescence detection serves as a powerful tool for investigating R-dependent aspects of molecular core–hole resonances. The experimental results do not agree with predictions based on previous theoretical developments, and possible causes for the discrepancy are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454838
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  • 8
    Electronic Resource
    Electronic Resource
    Stacked high-ε gate dielectric for gigascale integration of metal–oxide–semiconductor technologies (1998)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 72 (1998), S. 2835-2837 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Advances in lithography and thinner SiO2 gate oxides have enabled the scaling of metal–oxide–semiconductor technologies to sub-0.25 μm feature size. A major hurdle in the gate dielectric scaling using conventional thermally grown SiO2 has been excessive tunneling that occurs in ultrathin (〈25 Å) SiO2. High dielectric constant materials such as Ta2O5 have been suggested as a substitute for SiO2. However, these materials have high concentrations of bulk fixed charge, unacceptable levels of Si–Ta2O5 interface trap states, and low silicon interface carrier mobilities. This letter summerizes an elegant solution to these issues through synthesis of a thermally grown SiO2(15 Å)–Ta2O5(30 Å)–SiO2(5–10 Å) dielectric with improvements in leakage, tunneling, charge trapping behavior, and interface substructure. Transistors fabricated using this stacked gate dielectric exhibit excellent subthreshold, saturation, and drive currents.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.121473
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  • 9
    Electronic Resource
    Electronic Resource
    Characterization of stacked gate oxides by electron holography (1996)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 68 (1996), S. 3410-3412 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We have used off-axis electron holography at a resolution of 3 A(ring) to investigate amorphous bilayer gate oxides consisting of thermal and chemically deposited SiO2. The values of the mean inner potential were measured to be: thermal oxide: (10.51±0.35)V (undensified); (10.65±0.32)V ("densified''); deposited oxide: (11.19±0.38)V (undensified); (10.58±0.69)V (densified). Exploiting the chemical etch rate differences between different oxides, we have delineated stacked gate oxides consisting of closely similar layers. Our results establish that measurement of thickness differences produced by etching can be used to reveal the densification state of the oxide. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.115776
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  • 10
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    Development of a spin polarized low energy electron diffraction system (2016)
    American Institute of Physics (AIP)
    Details
    Publication Date: 2016-02-19
    Description: We have designed and constructed a spin polarized low energy electron diffraction system working in the reflected electron pulse counting mode. This system is capable of measuring asymmetries due to spin-orbit and exchange interactions. Photoemission from a strained GaAs/GaAsP super lattice is used as the source of spin polarized electrons. Spin-orbit asymmetry is evaluated for Ir(100) single crystal at various energies. Subsequently, exchange asymmetry has been evaluated on 40 monolayer Fe deposited on Ir(100). This instrument proves to be useful in understanding structure and magnetism at surfaces.
    Print ISSN: 0034-6748
    Electronic ISSN: 1089-7623
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Published by American Institute of Physics (AIP)
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