K-shell photoionization of Li, Be+ and B2+

2016 ◽  
Vol 30 (15) ◽  
pp. 1650204 ◽  
Author(s):  
Jun Li ◽  
Jian Dang Liu ◽  
Song Bin Zhang ◽  
Bang Jiao Ye
Keyword(s):  
High Resolution ◽  
Light Source ◽  
Cross Sections ◽  
Ground State ◽  
Matrix Method ◽  
Theoretical Calculations ◽  
Metastable States ◽  
The Core ◽  
Advanced Light Source ◽  
State Formula

K-shell photoionization (PI) of Li, Be[Formula: see text] and B[Formula: see text] from ground state [Formula: see text] have been studied by using the [Formula: see text]-matrix method with pseudostates. The K-shell PI process is featured with the contributions from the core-excited metastable states or dominated by the Auger states 2Po. The resonant parameters of the Auger states 2Po and the PI cross-sections have been calculated and compared with the available experimental and theoretical works. Our results agree very well with that of the published works. It is worth noting that compared with previous theoretical calculations, our results of B[Formula: see text] show better agreements with the latest high-resolution advanced light source measurements [A. Müller et al., J. Phys. B 43 (2010) 135602].

Performance of the vacuum ultraviolet high-resolution and high-flux beamline for chemical dynamics studies at the Advanced Light Source

1997 ◽  
Vol 68 (5) ◽  
pp. 1945-1951 ◽  
Author(s):  
P. A. Heimann ◽  
M. Koike ◽  
C. W. Hsu ◽  
D. Blank ◽  
X. M. Yang ◽  
...  
Keyword(s):  
High Resolution ◽  
Light Source ◽  
Vacuum Ultraviolet ◽  
High Flux ◽  
Chemical Dynamics ◽  
Advanced Light Source

THE LYMAN BANDS OF MOLECULAR HYDROGEN

1959 ◽  
Vol 37 (5) ◽  
pp. 636-659 ◽  
Author(s):  
G. Herzberg ◽  
L. L. Howe
Keyword(s):  
High Resolution ◽  
Vibrational Level ◽  
Ground State ◽  
Molecular Hydrogen ◽  
Equilibrium Constants ◽  
Dissociation Limit ◽  
Vibrational Levels ◽  
State Formula ◽  
Single Formula ◽  
Vibrational Constants

The Lyman bands of H2 have been investigated under high resolution with a view to improving the rotational and vibrational constants of H2 in its ground state. Precise Bv and ΔG values have been obtained for all vibrational levels of the ground state. One or two of the highest rotational levels of the last vibrational level (v = 14) lie above the dissociation limit. Both the [Formula: see text] and ΔG″ curves have a point of inflection at about v″ = 3. This makes it difficult to represent the whole course of each of these curves by a single formula and therefore makes the resulting equilibrium constants somewhat uncertain. This uncertainty is not very great for the rotational constants for which we find[Formula: see text]but is considerable for the vibrational constants ωe and ωexe for which three-, four-, five-, and six-term formulae give results diverging by ± 1 cm−1. The rotational and vibrational constants for the upper state [Formula: see text] of the Lyman bands are also determined. An appreciable correction to the position of the upper state is found.

CORE-HOLE EFFECT IN THE Ce L3 X-RAY ABSORPTION SPECTRA OF CeO2 AND CeFe2: NEW EXAMINATION BY USING RESONANT X-RAY EMISSION SPECTROSCOPY

2013 ◽  
Vol 27 (16) ◽  
pp. 1330012 ◽  
Author(s):  
A. KOTANI
Keyword(s):  
Absorption Spectra ◽  
Ground State ◽  
Theoretical Calculations ◽  
Emission Spectra ◽  
Core Hole ◽  
Final State ◽  
X Ray ◽  
The Core ◽  
X Ray Absorption ◽  
Hole Effect

We consider two different resonant X-ray emission spectra for Ce compounds: Ce 3d to 2p X-ray emission (denoted by 3d-RXES) and valence to 2p X-ray emission (v-RXES), both of which follow the Ce 2p to 5d resonant excitation. We propose that the comparison of the 3d- and v-RXES spectra is a new powerful method of directly detecting the core-hole effect in the final state of Ce L 3 X-ray absorption spectra (XAS). We applied this method to recent experimental RXES spectra for CeO 2 and CeFe 2, and showed unambiguously that the core-hole effect should be essential in the XAS of both materials. This result is confirmed by theoretical calculations, which reproduce well the experimental RXES and XAS spectra. We conclude that the ground state of CeO 2 is in the mixed state of 4f0 and [Formula: see text] configurations, where [Formula: see text] is a ligand hole, instead of a pure 4f0 configuration which was proposed recently by first-principles energy band calculations. Also, we conclude that the double peaks observed in L 3 XAS of CeFe 2 are caused by the 4f0 and 4f1 configurations, which are mixed in the ground state but separated in energy by the large core-hole potential in the final state of XAS.

HIGH-RESOLUTION HYPERNUCLEAR SPECTROSCOPY ELECTRON SCATTERING AT JLab, HALL A

2010 ◽  
Vol 19 (12) ◽  
pp. 2487-2496 ◽  
Author(s):  
◽  
F. Garibaldi ◽  
E. Cisbani ◽  
F. Cusanno ◽  
S. Frullani ◽  
...  
Keyword(s):  
Electron Beam ◽  
High Resolution ◽  
Energy Resolution ◽  
Electron Scattering ◽  
Ground State ◽  
Missing Energy ◽  
High Quality ◽  
The Core ◽  
Final Data ◽  
First Time

The characteristics of the Jefferson LAB electron beam, together with those of the experimental equipments, offer a unique opportunity to study hypernuclear spectroscopy via electromagnetic induced reactions. Experiment 94-107 started a systematic study on 1p-shell targets, 12 C , 9 Be and 16 O . We present the results from 12 C , 16 O and very preliminary results from 9 Be . For 12 C for the first time measurable strength in the core-excited part of the spectrum between the ground state and the pΛ state was shown in [Formula: see text] for the first time. A high-quality 16Λ N spectrum was produced for the first time with sub-MeV Energy resolution. A very precise B Λ value for 16Λ N , calibrated against the elementary ( e , e ′ K +) reaction on hydrogen, has also been obtained. Final data on 9 Be will be available soon. The missing energy resolution is the best ever obtained in hypernuclear production experiments.

Advanced microscopy—the new high-resolution zone-plate microscope at the advanced light source in Berkeley

1995 ◽  
Vol 53 ◽  
pp. 112-113
Author(s):  
W. Meyer-Ilse ◽  
H. Medecki ◽  
C Magowan ◽  
R. Balhorn ◽  
M. Moronne ◽  
...  
Keyword(s):  
High Resolution ◽  
Radiation Dose ◽  
Light Source ◽  
Incoherent Light ◽  
X Ray ◽  
Optical Layout ◽  
Advanced Light Source ◽  
Valuable Complement ◽  
Conventional Type ◽  
Transmission Microscope

A new x-ray microscope (XM-1) has been installed at the Advanced Light Source in Berkeley. This transmission microscope uses zone-plates for a resolution exceeding visible light microscopies. Samples can be as thick as 10 microns, for wet or dry specimens. These features make x-ray microscopy a valuable complement to other advanced techniques.There are two types of x-ray microscopes, scanning and conventional (imaging) microscopes. The scanning type minimizes radiation dose to the sample and is convenient for high resolution use of fluorescent labels; however, it requires a spatially coherent x-ray source and as a result involves long exposure times. The conventional type provides a higher potential for ultimate resolution as there is no scanning stage needed, and it can operate with an incoherent light source. It therefore has a shorter exposure time, but does require a higher radiation dose due to lens inefficiencies. The new XM-1 is of the second type. Its optical layout is very similar to the Gottingen x-ray microscope operated at the BESSY facility in Berlin, Germany.

scholarly journals The FUSE Mission: Atomic Data Needs in the 900–1200 Å Spectral Region

2002 ◽  
Vol 12 ◽  
pp. 79-81
Author(s):  
Kenneth R. Sembach
Keyword(s):  
High Resolution ◽  
Solar System ◽  
Interstellar Medium ◽  
Absorption Line ◽  
Ground State ◽  
Spectral Region ◽  
Theoretical Calculations ◽  
Oscillator Strengths ◽  
Atomic Data ◽  
Far Ultraviolet

AbstractThe Far Ultraviolet Spectroscopic Explorer (FUSE) is presently producing high resolution (R ∼ 20,000) absorption-line spectra of astronomical objects ranging from Solar System planets to quasars. The 900-1200 Å spectral region observed by FUSE is exceedingly rich in atomic and molecular transitions arising out of the ground state. It is already clear from early FUSE observations that the atomic data (e.g., oscillator strengths) for some transitions are considerably different than those predicted by theoretical calculations. I briefly describe the most pressing oscillator strength needs in this wavelength range for studies of the interstellar medium.

scholarly journals High‐resolution beamline 9.3.2 in the energy range 30–1500 eV at the Advanced Light Source: Design and performance

1996 ◽  
Vol 67 (9) ◽  
pp. 3372-3372 ◽  
Author(s):  
Z. Hussain ◽  
W.R.A. Huff ◽  
S.A. Kellar ◽  
E.J. Moler ◽  
P.A. Heimann ◽  
...  
Keyword(s):  
High Resolution ◽  
Energy Range ◽  
Light Source ◽  
Advanced Light Source ◽  
And Performance

Studies of the single and double photoionization of two-electron systems at the Advanced Light Source

1996 ◽  
Vol 74 (11-12) ◽  
pp. 713-721 ◽  
Author(s):  
Michael S. Lubell
Keyword(s):  
High Resolution ◽  
Light Source ◽  
Resolving Power ◽  
Electron Interaction ◽  
Threshold Region ◽  
Spectral Brightness ◽  
Operating Characteristics ◽  
Relative Contribution ◽  
Ionic Systems ◽  
Advanced Light Source

The Advanced Light Source (ALS) at Lawrence Berkeley Laboratory is a "third generation" synchrotron radiation machine that incorporates wigglers and undulators to enhance the spectral brightness of the emitted radiation. Commissioned in October 1993, its performance to date has been nothing short of spectacular. Its demonstrated characteristics make it an ideal tool for carrying out high resolution measurements of photoionization studies of two-electron atomic and ionic systems. ALS Beamline 9.0.1, a facility dedicated to the study of photoprocesses in atoms, molecules, and ions, utilizes an undulator with an 8 cm period and a monochromator with spherical gratings to produce light at energies between 20 and 300 eV. At a photon energy of, 50 eV, the beamline is designed to deliver about 1.5 × 1013 photons/s into a spot measuring approximately 50 × 800 μm with a resolving power of 10 000. Measurements of low-lying autoionizing resonances in He, carried out shortly after the ALS was commissioned, provided the first confirmation of the essential beamline characteristics. The 1.0 meV line width, more recently observed for the 2p3d double-excitation state of He at 64.12 eV, demonstrates that the actual resolving power of the beamline far exceeds the design value. The properties of the ALS, combined with improvements in the reliability and operating characteristics of ion sources, make it possible to extend high-resolution synchrotron experiments beyond the study of neutral systems. Investigations of low-Z ions are important, because they provide an easy way to vary the relative contribution of the electron–electron interaction. An international collaboration has recently been formed to perform such studies. Its list of priorities includes the doubly excited spectra and the threshold region for two-electron photoionization in Li+ and H−. Metastable He*, formed by resonant charge transfer from He+, will provide access totriplet states.

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