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.

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

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].

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 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

Up Close: Advanced Light Source at Lawrence Berkeley Laboratory

MRS Bulletin ◽  
1988 ◽  
Vol 13 (6) ◽  
pp. 44-46
Author(s):  
A. L. Robinson
Keyword(s):  
Light Source ◽  
San Francisco ◽  
Spectroscopic Studies ◽  
Department Of Energy ◽  
Advanced Materials ◽  
Spectral Brightness ◽  
Lawrence Berkeley Laboratory ◽  
Advanced Light Source ◽  
Materials Research ◽  
Chemical And Biological Systems

A marriage of the new and the old is under way at the Lawrence Berkeley Laboratory (LBL), Berkeley, California. The new is the Advanced Light Source (ALS), a facility for generating laser-like, partially coherent beams of x-ray and ultraviolet (collectively, the XUV) synchrotron radiation of unprecedented spectral brightness. (See Figure 1.) The old is the domed hall that has sheltered the historic 184-inch cyclotron, a nuclear accelerator built 46 years ago by the laboratory's founder E.O. Lawrence. The ALS is to reside in an enlarged version of the old hall, a familiar landmark in the Berkeley-San Francisco area whose architectural features are to be preserved.Another sign of the marriage is an increased emphasis on materials research. Though by no means forsaking its nuclear science origins, LBL has seen its budget for materials research grow steadily in recent years, especially with the establishment of the Center for Advanced Materials and the construction of two new laboratories to house its activities. [See the April 1988 MRS BULLETIN, p. 54, for an Up Close article on LBL's National Center for Electron Microscopy.] With its focus on the use of electromagnetic radiation for structural and spectroscopic studies of physical, chemical, and biological systems, including those investigated by materials researchers, the ALS fits neatly into this new emphasis. In fact, funding for the $98.7 million ALS comes to LBL through the Division of Materials Sciences of the U.S. Department of Energy (DOE).

XM-1: the high-resolution soft x-ray microscope at the Advanced Light Source

2000 ◽  
Author(s):  
Angelic L. Pearson ◽  
Weilun Chao ◽  
Gregory Denbeaux ◽  
Thomas Eimueller ◽  
Peter Fischer ◽  
...  
Keyword(s):  
High Resolution ◽  
Light Source ◽  
X Ray ◽  
Advanced Light Source

High-resolution soft X-ray emission spectrograph at advanced light source

2005 ◽  
Vol 66 (12) ◽  
pp. 2173-2178 ◽  
Author(s):  
Yi-De Chuang ◽  
John Pepper ◽  
Wayne McKinney ◽  
Zahid Hussain ◽  
Eric Gullikson ◽  
...  
Keyword(s):  
High Resolution ◽  
Light Source ◽  
X Ray ◽  
Advanced Light Source
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