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  • 1
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 105 (1996), S. 111-117 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Ionization probabilities of NO molecules electronically excited in the A 2Σ+ and B 2Π states have been determined by (1+1) resonance-enhanced, two-photon ionization. Various vibrational levels within these states have been excited prior to ionization. Measurements of the unsaturated ionization signal yields accurate values for the relative detection probabilities of NO of 1:(0.70±0.07): (0.67±0.11) for excitation via the γ(0−0), γ(1−1), and γ(2−2) bands, respectively, and (3.7±0.36)×10−7 and (5.8±0.65)×10−4 for ionization through β(0−0) and β(2−1) bands, respectively. Applying published data for the γ- and β-band transition probabilities allows the deduction of the ionization cross section of A 2Σ+ and B 2Π vibrational states. The respective ionization cross sections are (7.0±0.9)×10−19 cm2, (8.5±0.8)×10−19 cm2, (6.0±1.0)×10−19 cm2 for A 2Σ+(v′=0, 1, and 2) and (5.0±0.5)×10−21 cm2 and (1.7±0.2)×10−20 cm2 for B 2Π(v′=0 and 2). These values are based on the experimentally determined cross section for A 2Σ+(v′=0). Using a larger theoretical cross section for this state the other cross sections scale accordingly, within the experimental uncertainties. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 28 (1996), S. 283-289 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract Coherent radiation at 87.78 nm is generated by four-wave mixing in argon gas. Radiation of a mode-locked Nd:YLF laser at λ=1053 nm is regeneratively amplified at 1 kHz repetition rate. After frequency quadrupling in consecutive LBO and BBO crystals, the UV radiation at 263.35 nm is focused in Ar in front of a hollow capillary. Effects of gas density on the XUV intensity are discussed.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0649
    Keywords: PACS: 42.65.Ky; 51.70.+f
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: uv vac=351.165 nm) of a ps 1 kHz Nd:YLF laser system is frequency tripled in xenon and mercury vapour. About 4×104 photons per pulse, i.e. 4×107 photons/s, are generated in xenon yielding a conversion efficiency of η=3×10-10. The unusual frequency tripling in xenon takes place in a positive dispersive wavelength region. It is shown that Kerr-induced dispersion in the atomic system and a fifth-order process rather than a third-order process can explain the frequency tripling. For comparison a four-wave mixing process is investigated in negative dispersive mercury vapour. Due to absorption of the generated VUV radiation in the autoionization region of mercury the observed effective efficiency is, in our experimental arrangement, even lower than in xenon. An analysis of the VUV generation with respect to absorption is given.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 68 (1999), S. 605-609 
    ISSN: 1432-0649
    Keywords: PACS: 78.65.J; 79.20.D; 82.50.Fv
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: - and -polarized radiation. When the yield is related to the incident photon flux, desorption cross sections of (1.9±0.3)×10-17 cm2 and (3.3±0.5)×10-17 cm2 for - and -polarized light, respectively, are deduced. In order to assess the importance of substrate excitation the optical constants of NiO have been determined for the photon energy employed. When the desorption yield is then related to the photon flux absorbed in the NiO film, much larger cross sections are obtained, and an even larger effectiveness of -polarized light. For a direct optical excitation of charge transfer states the implications for the symmetry character of the states involved are discussed. It is concluded that excitations to A′′ states are preferred.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 9 (1999), S. 577-582 
    ISSN: 1434-6036
    Keywords: PACS. 79.60.-i Photoemission and photoelectron spectra - 61.14.Dc Theories of diffraction and scattering
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract: In this contribution we examine the separability of relativistic electron propagators. Both, magnetic and non-magnetic systems are studied on the basis of the Kohn-Sham-Dirac equation. We find a Dirac-Green's function in excellent agreement with recent calculations utilizing the left and right-handed solutions to the Dirac equation. Starting from these Dirac-Green's functions we re-derive a rotation matrix formalism that was shown to result in separable scattering matrices in the non-relativistic case. It turns out, that spin-dependent scattering matrices can be formulated which are closely related to their non-relativistic counterparts. These matrices incorporate spin-flip and non spin-flip processes on an equal footing, but are irreducible to sums over composite rotation matrices. The latter result is a major drawback for numerical applications since electron scattering in terms of composite rotations had drawn a lot of attention recently.
    Type of Medium: Electronic Resource
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