M. Hribar

K-MM radiative Auger effect in solid Ca, Ti and Cr targets after ionization with 0.7–1.5 MeV protons

Abstract Radiative Auger (RAE) X-ray spectra were measured for the first time on Ca, Cr, and Ti targets after ionization by 0.7–1.5 MeV protons. The energies of the RAE X-ray transitions were compared with the energies obtained from the Auger transitions. The RAE intensities relative to the diagram K β13 line were deduced and compared with the available data from X-ray fluorescence and electron capture ionization. The relative yields obtained for Ca, Ti, and Cr were (3.14 ± 0.47), (2.44 ± 0.37) and (2.91 ± 0.58)%, respectively.

A simple heat-pipe cell for X-ray absorption spectrometry of potassium vapor

The construction and operation of a simple high-temperature X-ray absorption cell for potassium vapor is described. The principle of “spectroscopic heat pipe” is exploited to separate kapton windows, indispensable for good transmission in the low-energy region, from the hot and aggressive vapor. High-resolution spectrum of the K-edge region of atomic potassium reveals fingerprints of multielectron photoexcitations.

Strong multielectron absorption effects in the L-edge EXAFS spectra of elements from I to Ce

Abstract Strong multielectron photoabsorption structure, comparable in size to EXAFS amplitudes, is found in L-edge EXAFS spectra of Xe-isoelectronic ions Cs+La3+. The spectra have been measured on amorphous samples (solutions, gels, and glasses) with a small single-wave EXAFS component. The structure is identified as a resonant transition to [2p4d]5d2 state: it is missing in the spectrum of iodine, but continues into the lanthanide series.

L-subshell fluorescence yields of lead

L-subshell fluorescence yields of lead are determined in a series of experiments where lead atoms in lead tetraethyl, Pb(C2H5)4, in a small admixture to the propane in proportional counter are ionized in theL-shell by a beam of monochromatic X-rays. The technique of selective photoexcitation of consecutive subshells is applied and fluorescence events are resolved into subshell contributions. The subshell fluorescence yields are determined asωLI=0.16±0.04,ωLII=0.407±0.010 andωLIII=0.347±0.005.

A study of the M-shell fluorescence yields of lead

Abstract The modes of decay of the M-shell vacancies in lead atoms were studied by means of a wall-less proportional counter spectrometer with lead in the form of lead-tetraethyle admixed to the working gas of the counter. The vacancies in consecutive M-subshells of the lead atoms were produced by the photoelectric absorption of the characteristic K-radiation of elements from Cl to V. The following M-shell fluorescence yields were extracted: ω M = 0.032 ± 0.003, ω 2–5 = 0.030 ± 0.003, ω 3–5 = 0.030 ± 0.002 ω 4,5 ≥ 0.029 .

Electrons ejected in resonant Raman scattering of X-rays on krypton

In the resonant Raman scattering of x-rays on krypton gas the ejected electrons were investigated by a proportional counter spectrometer. The cross sections for the process were determined for three energies of the incident photons (181 eV, 89 eV, and 33 eV below theK edge). The results agree with the theoretical predictions, thus independently confirming the theory that has so far only been tested by scattered photon data. From the cross sections the width of theK-shell excited state of krypton is extracted asΓK=(2.75±0.10) eV.

The determination of theK-shell fluorescence yield of xenon by use of the proportional counter method

The wall-less proportional counter filled with propane with a small admixture of xenon was used as a spectrometer of electrons emitted by xenon atoms when photoelectrically excited by americium-241γ-rays and erbiumKα rays. TheK-shell fluorescence yield of xenon as extracted from spectra ammounts toωk=0.889(1±0.01).

The study of the L-shell fluorescence yields of xenon

Abstract The wall-less proportional counter was used as an electron spectrometer. From the spectra of electrons generated by photoelectric excitation of separate L-subshells the following subshell and average fluorescence yields were extracted: ω 3 = 0.099 ± 0.002; ν 2 = 0.106 ± 0.007; ν 1 = 0.09 ± 0.03; ω 23 = 0.102 ± 0.001; and ω L = 0.100 ± 0.003 . Taking into account the theoretical values for Coster-Kronig transition probabilities the L 2 and L 1 subshell fluorescence yields were determined as ω 2 = 0.089 ± 0.008 and ω 1 = 0.05 ± 0.03.

Intermediate phases in the formation of the CuBaY high-Tc superconductor from xerogel

Abstract In the synthesis of YBa2Cu3O7−x superconductor ceramics by the sol-gel method, yttrium K EXAFS spectra of the intermediate products give evidence of the dynamics of the Y ion in the reaction. Together with previous data on Cu K and Ba L3 EXAFS, the results give information on the processes in the amorphous phase, complementing the diffraction data on crystalline growth.