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  • 1975-1979  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 19 (1979), S. 119-125 
    ISSN: 1432-0630
    Keywords: 02
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A method is developed for handling the effect of a finite amplitude on the results of potential modulation differentiation. The procedure is applied to harmonic modulation and allows to extrapolate measured Fourier coefficients to zero modulation amplitude. It is therefore possible to use modulation amplitudes as dictated by signal-to-noise considerations avoiding dynamical broadening of the detected signal. The formalism can be easily extended to combine with dynamic background subtraction. Examples are given for soft x-ray appearance potential measurements.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 18 (1979), S. 375-380 
    ISSN: 1432-0630
    Keywords: 71. 20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract A vacuum ultraviolet isochromat spectrometer employing an energy selective Geiger-Müller photon counter is described. The mean energy of the spectrometer is 9.7 eV with a standard deviation of ±0.23 eV. Together with the thermal energy distribution of the electrons emitted from a directly heated tungsten cathode, an overall resolution of ±0.33 eV is obtained. Pulsed operation of the x-ray tube avoids additional broadening due to the voltage drop across the filament. Further, pulsed operation of the accelerating voltage is employed to avoid counting losses due to the relatively large dead time of the radiation detector. Operating frequencies of up to 2 kHz are possible. With sensitivities of typically 107 pulses per Coulomb, the anode currents are in the range of 100–200 μA. These attractive properties suggest to employ the method to study surface electronic properties of solids.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 19 (1979), S. 19-23 
    ISSN: 1432-0630
    Keywords: 71.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Soft x-ray appearance potential spectra from solids carry information on the local density of unoccupied states in the surface region of the sample. The intensity of the emitted characteristic radiation is, according to a simple model, proportional to a convolution product of the transition densities of the incoming electron and the ionized core electron. In a first approximation, the two transition densities are proportional to the density of states in the unoccupied part of the conduction band. Attempts to retrieve the density of states from measured spectra must rely on deconvolution procedures. In this paper, we introduce a new simple method. It is essentially a stabilized version of the Hagstrum-Becker method which appears to work quickly and reliably. As an example, the method is applied to an ironL III appearance potential spectru. Comparison of the results with a theoretical calculation of the density of states and with measured Bremsstrahlungsisochromats obtained by Turtle and Liefeld strongly supports the self-convolution model in this case.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Applied physics 20 (1979), S. 37-40 
    ISSN: 1432-0630
    Keywords: 71.20
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Abstract Any conventional soft x-ray appearance potential spectrometer may be converted to an isochromat spectrometer by placing an absorber foil of suitably chosen thickness in front of the x-ray detector. In the present work, we demonstrate the principle and work out in detail the properties of an aluminum absorption foil. Isochromats of a hafnium sample are compared to results obtained with a crystal x-ray spectrometer. Also, the equivalence of an isochromat and an SXAPS measurement at the same energy will be shown. The densities of unoccupied states as derived from the respective experiments are in pretty good agreement.
    Type of Medium: Electronic Resource
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