Two Laser-Produced Plasmas Method For Absorption Spectra And Photoionization Cross-Sections Measurements On Light Ions In The Vuv Dnd Soft X-Ray Spectral Range

1988 ◽  
Author(s):  
E Jannitti ◽  
P Nicolosi ◽  
G Tondello
Keyword(s):  
Absorption Spectra ◽  
Spectral Range ◽  
Cross Sections ◽  
X Ray ◽  
Light Ions

scholarly journals L-shell x-ray production cross sections for light ions on Sm, Yb, and Pb

1975 ◽  
Vol 12 (6) ◽  
pp. 2393-2398 ◽  
Author(s):  
Tom J. Gray ◽  
G. M. Light ◽  
R. K. Gardner ◽  
F. D. McDaniel
Keyword(s):  
Cross Sections ◽  
Production Cross ◽  
X Ray ◽  
Light Ions

scholarly journals Review of Methods of Intensity Calibration in the Spectral Range 10–4000 Å

1971 ◽  
Vol 41 ◽  
pp. 369-369
Author(s):  
R. W. P. Mc Whirter
Keyword(s):  
Spectral Range ◽  
Cross Sections ◽  
Hydrogen Absorption ◽  
Vacuum Ultraviolet ◽  
Rate Coefficients ◽  
Laboratory Work ◽  
The Sun ◽  
X Ray ◽  
Spectral Intensities ◽  
Intensity Calibration

In this paper the bases of the various methods of intensity calibration in the vacuum ultraviolet will be examined. The remarks will be directed primarily at the problem of the measurement of spectral intensities from the sun from above the Earth's atmosphere. It is here that the requirements for intensity calibration are most demanding because of the greater sophistication and because the available range of the spectrum is more extensive. For the stars and other distant astronomical objects, hydrogen absorption limits the spectrum to wavelengths longer than about 900 Å although it transmits again in the soft X-ray region. Some reference will also be made to the problem of intensity calibration as it applies to laboratory spectroscopy, particularly where the object of the laboratory work is to measure astrophysically interesting rate coefficients or cross sections.

scholarly journals Absorption Spectra of Light Ions in the Extreme Ultraviolet

1984 ◽  
Vol 86 ◽  
pp. 251-254
Author(s):  
E. Jannitti ◽  
P. Nicolosi ◽  
F. Pinzhong ◽  
G. Tondello
Keyword(s):  
Laser Beam ◽  
Absorption Spectra ◽  
Cross Sections ◽  
Extreme Ultraviolet ◽  
Normal Incidence ◽  
Grazing Incidence ◽  
Light Ions ◽  
Background Continuum ◽  
Set Up ◽  
The Continuum

We have used the method of two laser produced plasmas (Jannitti et al. 1984a) to measure the absorption spectra of the ions Be++ (Jannitti et al. 1984b), Be+ (Jannitti et al. 1984c) and B+ in the grazing incidence and normal incidence region. Both discrete and continua transitions have been measured and values of the photoionization cross sections are derived.The experimental set up referring to the normal incidence investigation is shown in Fig. 1. A laser beam of 10 J of energy and 15 ns (FWHM) duration is split in two parts and generates two plasmas: one on target T of high atomic number (Cu) used as a background continuum emitting source and a second on target A for producing the absorbing species to be studied. For the latter a sphero-cylindrical lens is used producing a focal spot 100 µm wide and up to 10 mm long. The continuum radiation produced on a target tilted 45° both with respect to the laser beam and to the axis of observation was collected by a toroidal mirror whose radii of curvature, R = 640 mm in the plane of incidence and ρ = 530 mm in the plane perpendicular to the former are such to compensate the astigmatism of the 2 m radius grating.

SIGMAL: A Program for Calculating L-Shell lonization Cross-Sections

1981 ◽  
Vol 39 ◽  
pp. 198-199 ◽  
Author(s):  
R.F. Egerton
Keyword(s):  
Cross Sections ◽  
Fortran Program ◽  
Absorption Data ◽  
X Ray ◽  
Atomic Electrons ◽  
Energy Dependent ◽  
Hydrogenic Model ◽  
Electron Energy Loss ◽  
X Ray Absorption ◽  
Shell Ionization

SIGMAL is a short (∼ 100-line) Fortran program designed to rapidly compute cross-sections for L-shell ionization, particularly the partial crosssections required in quantitative electron energy-loss microanalysis. The program is based on a hydrogenic model, the L1 and L23 subshells being represented by scaled Coulombic wave functions, which allows the generalized oscillator strength (GOS) to be expressed analytically. In this basic form, the model predicts too large a cross-section at energies near to the ionization edge (see Fig. 1), due mainly to the fact that the screening effect of the atomic electrons is assumed constant over the L-shell region. This can be remedied by applying an energy-dependent correction to the GOS or to the effective nuclear charge, resulting in much closer agreement with experimental X-ray absorption data and with more sophisticated calculations (see Fig. 1 ).

Preparation And elemental analysis of ancient fibers

1987 ◽  
Vol 45 ◽  
pp. 410-411
Author(s):  
Allen Angel ◽  
Kathryn A. Jakes
Keyword(s):  
Cross Sections ◽  
Physical Structure ◽  
Energy Dispersive ◽  
Archaeological Sites ◽  
X Ray ◽  
Long Term Storage ◽  
Backscattered Electron ◽  
Electron Imaging

Fabrics recovered from archaeological sites often are so badly degraded that fiber identification based on physical morphology is difficult. Although diagenetic changes may be viewed as destructive to factors necessary for the discernment of fiber information, changes occurring during any stage of a fiber's lifetime leave a record within the fiber's chemical and physical structure. These alterations may offer valuable clues to understanding the conditions of the fiber's growth, fiber preparation and fabric processing technology and conditions of burial or long term storage (1).Energy dispersive spectrometry has been reported to be suitable for determination of mordant treatment on historic fibers (2,3) and has been used to characterize metal wrapping of combination yarns (4,5). In this study, a technique is developed which provides fractured cross sections of fibers for x-ray analysis and elemental mapping. In addition, backscattered electron imaging (BSI) and energy dispersive x-ray microanalysis (EDS) are utilized to correlate elements to their distribution in fibers.

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