title: Ultrasoft x-ray Bremsstrahlung isochromatic spectra from 300-2000 eV electrons on Ar and Kr.
abstract: For the first time the bremsstrahlung effect was studied experimentally in the spectral region of 6.5-10 nm with 300-2000 eV electron scattering on Ar and Kr atoms. The isochromatic curves displayed maxima at electron energies of approximately = 0.7 keV (Ar) and approximately =1 keV (Kr); their positions are almost independent of the radiation wavelength in the range studied. These experimental data cannot be treated in the framework of theory based on the first Born approximation. A phenomenological modification of the quasiclassical (soft-photon) approximation is proposed which gives a qualitative treatment of data.
authors.affiliation: Verkin Institute for Low Temperature Physics and Engineering, National Academy of Sciences of Ukraine, Kharkov, Ukraine.
authors.forename: E V
authors.initials: EV
authors.lastname: Gnatchenko
authors.forename: A A
authors.initials: AA
authors.lastname: Tkachenko
authors.forename: E T
authors.initials: ET
authors.lastname: Verkhovtseva
authors.forename: B A
authors.initials: BA
authors.lastname: Zon