M. Kavčič - Academia.edu (original) (raw)
Papers by M. Kavčič
AIP Conference Proceedings, 2003
High-resolution measurements of the K x-ray spectra of metallic Ca, Ti, Cr, and Fe were performed... more High-resolution measurements of the K x-ray spectra of metallic Ca, Ti, Cr, and Fe were performed with a von Hamos Bragg crystal spectrometer. The target x-ray emission was induced by by 2-19 MeV/amu C, O and Ne ions. The energies of the well resolved KalphaLN X-ray satellite lines were determined. Based on the measured values the empirical formula for the KalphaLN satellite energy shift of the 3d transition elements is given. For the Ca and Ti target bombarded with C ions also the KalphahLN hypersatellite lines the KbetaLN satellite lines and even the KbetahLN hypersatellite lines have been measured and their energies determined. The possible variation of the energy differences between neighboring satellite and hypersatellite lines with the projectile energy and atomic number was probed. No significant dependence on the projectile characteristics was observed. In contrast to that the absolute energies of the satellite and hypersatellite lines lines were found to depend on the projectile velocity. This dependence was attributed to the M shell ionization of the target atoms accompanied to the K and L-shell ionization produced in collisions.
AIP Conference Proceedings, 1999
High resolution Kα X-ray spectra of Ca, Cr and Fe induced by 0.7–1.5 MeV protons and of Ti induce... more High resolution Kα X-ray spectra of Ca, Cr and Fe induced by 0.7–1.5 MeV protons and of Ti induced by 0.7 − 4 MeV protons were measured by a flat crystal spectrometer. The experiment was mainly performed at the J. Stefan Institute. Ti spectra induced by 2, 3 and 4 MeV protons were measured at the Ruder Bosˇkovic´ Institute in Zagreb. From the relative yields of the KL1 satellites, which are the result of multiple inner-shell ionization, the average L-shell ionization probabilities in near-central collisions were determined. The effects of the rearrangement of the inner-shell holes prior to the K X-ray emission and the changes of the fluorescence yields due to the multiple ionization were taken into account in the evaluation of the ionization probabilities. It was shown that the rearrangement of the L-shell holes significantly changes the initial inner-shell holes distribution. The change of the K-shell fluorescence yield due to additional L shell hole was estimated to be negligible. The inner shell ionization induced by proton collisions with light atoms is mainly result of the direct Coulomb interaction between the inner shell electron and the moving projectile. The direct Coulomb ionization probabilities in the near-central collisions were determined from the relative yields of the KL1 satellites after subtracting the shake contribution. The values obtained were compared with semiclassical approximation calculations exploiting relativistic hydrogenic and Hartree-Fock wave functions. The importance of a realistic atomic description using Hartree-Fock wave functions was demonstrated.
Review of Scientific Instruments, 2007
High-resolution x-ray measurements were performed with a von Hamos-type bent crystal spectrometer... more High-resolution x-ray measurements were performed with a von Hamos-type bent crystal spectrometer using for the detection of the diffracted photons either a back-illuminated charge-coupled device ͑CCD͒ camera or a front-illuminated one. For each CCD the main x-ray emission lines ͑e.g., K␣, K, L␣, and L͒ of a variety of elements were measured in order to probe the performances of the two detectors between 1 and 18 keV. From the observed x-ray lines the linearity of the energy response, the noise level, the energy resolution, and the quantum efficiency ratio of the two CCDs were determined.
![Research paper thumbnail of Erratum: “Design and performance of a versatile curved−crystal spectrometer for high-resolution spectroscopy in the tender x-ray range” [Rev. Sci. Instrum. 83, 033113 (2012)]](https://attachments.academia-assets.com/48300488/thumbnails/1.jpg)
](Review of Scientific Instruments, 2012
Erratum: "Design and performance of a versatile curved-crystal spectrometer for high-resolution s... more Erratum: "Design and performance of a versatile curved-crystal spectrometer for high-resolution spectroscopy in the tender x-ray range" [Rev. Sci. Instrum. 83, 033113 (2012)]
Review of Scientific Instruments, 2012
Demonstration of a real-time interferometer as a bunch-length monitor in a high-current electron ... more Demonstration of a real-time interferometer as a bunch-length monitor in a high-current electron beam accelerator Rev. Sci. Instrum. 83, 043302 (2012) Voltage holding study of 1 MeV accelerator for ITER neutral beam injector Rev. Sci. Instrum. 83, 02B121 Performance of a fast digital integrator in on-field magnetic measurements for particle accelerators Rev. Sci. Instrum. 83, 024702 Low-energy, high-current, ion source with cold electron emitter Rev. Sci. Instrum. 83, 02B301 Characteristics of a symmetrical Cockcroft-Walton power supply of 50 Hz 1.2 MV/50 mA Rev. Sci. Instrum. 82, 055116 (2011) Additional information on Rev. Sci. Instrum.
The Journal of Chemical Physics, 2011
We present measurements of the resonant inelastic x-ray scattering (RIXS) spectra of the CH 3 I m... more We present measurements of the resonant inelastic x-ray scattering (RIXS) spectra of the CH 3 I molecule in the hard-x-ray region near the iodine L 2 and L 3 absorption edges. We show that dispersive RIXS spectral features that were recognized as a fingerprint of dissociative molecular states can be interpreted in terms of ultrashort natural lifetime of ∼200 attoseconds in the case of the iodine L-shell core-hole. Our results demonstrate the capacity of the RIXS technique to reveal subtle dynamical effects in molecules with sensitivity to nuclear rearrangement on a subfemtosecond time scale.
The Journal of Chemical Physics, 2013
The dissociation process following the Cl K-shell excitation to σ * resonances is studied by high... more The dissociation process following the Cl K-shell excitation to σ * resonances is studied by high resolution spectroscopy of resonant elastic and inelastic x-ray scattering on CH 3 Cl, CH 2 Cl 2 , CHCl 3 , and CCl 4 molecules. Calculations employing the transition potential and Delta-Kohn-Sham DFT approach are in good agreement with the measured total fluorescence yield and show the presence of a second quasidegenerate group of states with σ * character above the lowest σ * unoccupied molecular orbital for molecules with more than one Cl atom. A bandwidth narrowing and a nonlinear dispersion behavior is extracted from the Kα spectral maps for both σ * resonances. The fitted data indicate that the widths of the Franck-Condon distributions for the first and second σ * resonances are comparable for all the molecules under study. In addition, an asymmetric broadening of the emission peaks is observed for resonant elastic x-ray scattering with zero detuning on both σ * resonances. This is attributed to the fast dissociation, transferring about 0.15 of the scattering probability into higher vibrational modes.
Journal of Applied Physics, 2009
We report on the application of synchrotron radiation based high-resolution grazing-emission x-ra... more We report on the application of synchrotron radiation based high-resolution grazing-emission x-ray fluorescence ͑GEXRF͒ method to measure low-level impurities on silicon wafers. The presented high-resolution GEXRF technique leads to direct detection limits of about 10 12 atoms/ cm 2 . The latter can be presumably further improved down to 10 7 atoms/ cm 2 by combining the synchrotron radiation-based GEXRF method with the vapor phase decomposition preconcentration technique. The capability of the high-resolution GEXRF method to perform surface-sensitive elemental mappings with a lateral resolution of several tens of micrometers was probed.
Inorganic Chemistry, 2010
The electronic structure and ligand environment of sulfur was investigated in various sulfur-cont... more The electronic structure and ligand environment of sulfur was investigated in various sulfur-containing compounds with different structures and chemical states by using X-ray emission spectroscopy (XES). Calculations were performed using density functional theory (DFT) as implemented in the StoBe code. The sulfur chemical state and atomic environment is discussed in terms of the molecular orbitals and partial charges that are obtained from the calculations. The main spectral features can be modeled using our calculational approach. The sensitivity of the Kβ emission to the cation and the local symmetry is discussed.
Analytical Chemistry, 2009
An X-ray spectroscopy and theoretical study of the chemical state of several sulfur bearing miner... more An X-ray spectroscopy and theoretical study of the chemical state of several sulfur bearing minerals and a synthetic sodium sulfite sample was performed. X-ray absorption and high-resolution Kr X-ray emission spectra were recorded and compared to ab initio quantum chemical calculations. A consistent interpretation of the chemical shift in the Kr emission spectra is obtained based on three different theoretical approaches (density functional theory, multiple scattering theory, and atomic multiplet theory). An analysis of the theoretical sulfur orbital population and valence bond is in agreement with the fluorescence energy position of the Kr lines even within the sulfide (S 2-) series. It is shown that the Kr energy shifts can be used for a quantitative determination of the proportion of different sulfur species in heterogeneous samples.
Physical Review B, 2013
We present a method suitable for the measurement of a high-energy resolved absorption spectrum in... more We present a method suitable for the measurement of a high-energy resolved absorption spectrum in the emission mode upon target excitation with an intense monochromatic pulse of x-ray light. The approach is based on a measurement of a single resonant Raman x-ray spectrum at a fixed off-resonant excitation energy by a dispersive-type high-resolution emission spectrometer. Using a simple Lorentzian tail correction function and an energy-scale transformation, we reconstructed the L 3 absorption edge of Xe from the 3d-2p 3/2 resonant Raman x-ray spectrum recorded at excitation energy 25 eV below the L 3 edge. The energy resolution is well below the L 3 core-hole lifetime broadening and allows for a straightforward extraction of the [2p 3/2 ]n resonance energies and emission strengths. The reconstructed spectrum is nearly equivalent to the high-energy resolution fluorescence detected absorption spectrum, which is recorded by scanning the photon excitation energy across the absorption edge.
AIP Conference Proceedings, 2003
High-resolution measurements of the K x-ray spectra of metallic Ca, Ti, Cr, and Fe were performed... more High-resolution measurements of the K x-ray spectra of metallic Ca, Ti, Cr, and Fe were performed with a von Hamos Bragg crystal spectrometer. The target x-ray emission was induced by by 2-19 MeV/amu C, O and Ne ions. The energies of the well resolved KalphaLN X-ray satellite lines were determined. Based on the measured values the empirical formula for the KalphaLN satellite energy shift of the 3d transition elements is given. For the Ca and Ti target bombarded with C ions also the KalphahLN hypersatellite lines the KbetaLN satellite lines and even the KbetahLN hypersatellite lines have been measured and their energies determined. The possible variation of the energy differences between neighboring satellite and hypersatellite lines with the projectile energy and atomic number was probed. No significant dependence on the projectile characteristics was observed. In contrast to that the absolute energies of the satellite and hypersatellite lines lines were found to depend on the projectile velocity. This dependence was attributed to the M shell ionization of the target atoms accompanied to the K and L-shell ionization produced in collisions.
AIP Conference Proceedings, 1999
High resolution Kα X-ray spectra of Ca, Cr and Fe induced by 0.7–1.5 MeV protons and of Ti induce... more High resolution Kα X-ray spectra of Ca, Cr and Fe induced by 0.7–1.5 MeV protons and of Ti induced by 0.7 − 4 MeV protons were measured by a flat crystal spectrometer. The experiment was mainly performed at the J. Stefan Institute. Ti spectra induced by 2, 3 and 4 MeV protons were measured at the Ruder Bosˇkovic´ Institute in Zagreb. From the relative yields of the KL1 satellites, which are the result of multiple inner-shell ionization, the average L-shell ionization probabilities in near-central collisions were determined. The effects of the rearrangement of the inner-shell holes prior to the K X-ray emission and the changes of the fluorescence yields due to the multiple ionization were taken into account in the evaluation of the ionization probabilities. It was shown that the rearrangement of the L-shell holes significantly changes the initial inner-shell holes distribution. The change of the K-shell fluorescence yield due to additional L shell hole was estimated to be negligible. The inner shell ionization induced by proton collisions with light atoms is mainly result of the direct Coulomb interaction between the inner shell electron and the moving projectile. The direct Coulomb ionization probabilities in the near-central collisions were determined from the relative yields of the KL1 satellites after subtracting the shake contribution. The values obtained were compared with semiclassical approximation calculations exploiting relativistic hydrogenic and Hartree-Fock wave functions. The importance of a realistic atomic description using Hartree-Fock wave functions was demonstrated.
Review of Scientific Instruments, 2007
High-resolution x-ray measurements were performed with a von Hamos-type bent crystal spectrometer... more High-resolution x-ray measurements were performed with a von Hamos-type bent crystal spectrometer using for the detection of the diffracted photons either a back-illuminated charge-coupled device ͑CCD͒ camera or a front-illuminated one. For each CCD the main x-ray emission lines ͑e.g., K␣, K, L␣, and L͒ of a variety of elements were measured in order to probe the performances of the two detectors between 1 and 18 keV. From the observed x-ray lines the linearity of the energy response, the noise level, the energy resolution, and the quantum efficiency ratio of the two CCDs were determined.
Review of Scientific Instruments, 2012
Erratum: "Design and performance of a versatile curved-crystal spectrometer for high-resolution s... more Erratum: "Design and performance of a versatile curved-crystal spectrometer for high-resolution spectroscopy in the tender x-ray range" [Rev. Sci. Instrum. 83, 033113 (2012)]
Review of Scientific Instruments, 2012
Demonstration of a real-time interferometer as a bunch-length monitor in a high-current electron ... more Demonstration of a real-time interferometer as a bunch-length monitor in a high-current electron beam accelerator Rev. Sci. Instrum. 83, 043302 (2012) Voltage holding study of 1 MeV accelerator for ITER neutral beam injector Rev. Sci. Instrum. 83, 02B121 Performance of a fast digital integrator in on-field magnetic measurements for particle accelerators Rev. Sci. Instrum. 83, 024702 Low-energy, high-current, ion source with cold electron emitter Rev. Sci. Instrum. 83, 02B301 Characteristics of a symmetrical Cockcroft-Walton power supply of 50 Hz 1.2 MV/50 mA Rev. Sci. Instrum. 82, 055116 (2011) Additional information on Rev. Sci. Instrum.
The Journal of Chemical Physics, 2011
We present measurements of the resonant inelastic x-ray scattering (RIXS) spectra of the CH 3 I m... more We present measurements of the resonant inelastic x-ray scattering (RIXS) spectra of the CH 3 I molecule in the hard-x-ray region near the iodine L 2 and L 3 absorption edges. We show that dispersive RIXS spectral features that were recognized as a fingerprint of dissociative molecular states can be interpreted in terms of ultrashort natural lifetime of ∼200 attoseconds in the case of the iodine L-shell core-hole. Our results demonstrate the capacity of the RIXS technique to reveal subtle dynamical effects in molecules with sensitivity to nuclear rearrangement on a subfemtosecond time scale.
The Journal of Chemical Physics, 2013
The dissociation process following the Cl K-shell excitation to σ * resonances is studied by high... more The dissociation process following the Cl K-shell excitation to σ * resonances is studied by high resolution spectroscopy of resonant elastic and inelastic x-ray scattering on CH 3 Cl, CH 2 Cl 2 , CHCl 3 , and CCl 4 molecules. Calculations employing the transition potential and Delta-Kohn-Sham DFT approach are in good agreement with the measured total fluorescence yield and show the presence of a second quasidegenerate group of states with σ * character above the lowest σ * unoccupied molecular orbital for molecules with more than one Cl atom. A bandwidth narrowing and a nonlinear dispersion behavior is extracted from the Kα spectral maps for both σ * resonances. The fitted data indicate that the widths of the Franck-Condon distributions for the first and second σ * resonances are comparable for all the molecules under study. In addition, an asymmetric broadening of the emission peaks is observed for resonant elastic x-ray scattering with zero detuning on both σ * resonances. This is attributed to the fast dissociation, transferring about 0.15 of the scattering probability into higher vibrational modes.
Journal of Applied Physics, 2009
We report on the application of synchrotron radiation based high-resolution grazing-emission x-ra... more We report on the application of synchrotron radiation based high-resolution grazing-emission x-ray fluorescence ͑GEXRF͒ method to measure low-level impurities on silicon wafers. The presented high-resolution GEXRF technique leads to direct detection limits of about 10 12 atoms/ cm 2 . The latter can be presumably further improved down to 10 7 atoms/ cm 2 by combining the synchrotron radiation-based GEXRF method with the vapor phase decomposition preconcentration technique. The capability of the high-resolution GEXRF method to perform surface-sensitive elemental mappings with a lateral resolution of several tens of micrometers was probed.
Inorganic Chemistry, 2010
The electronic structure and ligand environment of sulfur was investigated in various sulfur-cont... more The electronic structure and ligand environment of sulfur was investigated in various sulfur-containing compounds with different structures and chemical states by using X-ray emission spectroscopy (XES). Calculations were performed using density functional theory (DFT) as implemented in the StoBe code. The sulfur chemical state and atomic environment is discussed in terms of the molecular orbitals and partial charges that are obtained from the calculations. The main spectral features can be modeled using our calculational approach. The sensitivity of the Kβ emission to the cation and the local symmetry is discussed.
Analytical Chemistry, 2009
An X-ray spectroscopy and theoretical study of the chemical state of several sulfur bearing miner... more An X-ray spectroscopy and theoretical study of the chemical state of several sulfur bearing minerals and a synthetic sodium sulfite sample was performed. X-ray absorption and high-resolution Kr X-ray emission spectra were recorded and compared to ab initio quantum chemical calculations. A consistent interpretation of the chemical shift in the Kr emission spectra is obtained based on three different theoretical approaches (density functional theory, multiple scattering theory, and atomic multiplet theory). An analysis of the theoretical sulfur orbital population and valence bond is in agreement with the fluorescence energy position of the Kr lines even within the sulfide (S 2-) series. It is shown that the Kr energy shifts can be used for a quantitative determination of the proportion of different sulfur species in heterogeneous samples.
Physical Review B, 2013
We present a method suitable for the measurement of a high-energy resolved absorption spectrum in... more We present a method suitable for the measurement of a high-energy resolved absorption spectrum in the emission mode upon target excitation with an intense monochromatic pulse of x-ray light. The approach is based on a measurement of a single resonant Raman x-ray spectrum at a fixed off-resonant excitation energy by a dispersive-type high-resolution emission spectrometer. Using a simple Lorentzian tail correction function and an energy-scale transformation, we reconstructed the L 3 absorption edge of Xe from the 3d-2p 3/2 resonant Raman x-ray spectrum recorded at excitation energy 25 eV below the L 3 edge. The energy resolution is well below the L 3 core-hole lifetime broadening and allows for a straightforward extraction of the [2p 3/2 ]n resonance energies and emission strengths. The reconstructed spectrum is nearly equivalent to the high-energy resolution fluorescence detected absorption spectrum, which is recorded by scanning the photon excitation energy across the absorption edge.