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Spectroscopic Research Projects on Heavy Elements at NIST. Wolfgang L. Wiese National Institute of Standards and Technology (NIST), USA. Participants. Experimental Research: J. Reader, G. Nave, J. Gillaspy, M. Bridges,* W. Wiese*
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Wolfgang L. Wiese
National Institute of Standards and Technology (NIST), USA
Experimental Research: J. Reader, G. Nave,
J. Gillaspy, M. Bridges,*
Theoretical Approaches: Ch. Froese-Fischer,*
Y.-K. Kim , P. Stone*
Data Assessment and J. Reader, E. Saloman,*
Compilations: J. Fuhr,* D. Kelleher,*
A. Kramida,* W. Wiese*
Database Development: Y. Ralchenko,*
*indicates Contractors or Guest Researchers
1. An updated and expanded critical compilation of spectroscopic reference data for Fe I and Fe II, focusing on better transition probabilities.
2. Calculations of ionization and excitation cross-sections of neutral and singly ionized Mo and W with the Binary-Encounter-Bethe (BEB) model.
3. Experimental observations of the spectra of highly charged tungsten ions, in the range from W+35 to W+63, with an Electron Beam Ion Trap (EBIT) and their analysis.
O’Brian 180 lifetimes and branching fractions
Blackwell absorption (based on one lifetime)
Kock several lifetimes and branching fractions
Raassen = semi-empirical calculation
Already in the database:
1. Total ionization cross sections of neutral atoms and molecules, singly charged molecular ions (about 100)
2. Differential ionization cross sections of H, He, H2
3. Excitation cross sections of light atoms
New results to be added by summer, 2007:
4. Total ionization cross sections (direct + excitation-autoionization) of Mo, Mo+, W, W+ (joint work with KAERI, see graphs)—BEB model plus BE/E scaling of Born cross sections [Mo/Mo+ in Kwon, Rhee & Kim, Int. J. Mass Spectrometry, 245, 26 (2005)]
5. Excitation cross sections of H2 (see graphs)—BE scaling of Born cross sections
6. Ionization cross sections of Si, Ge, Sn, Pb, Cl, Br, I, Cl2, Br2, I2
INTERPRETATION AS W XXX - W XXXV
ISLER, NEIDIGH, AND COWAN (1977)
Cu and Zn sequences to W
READER & LUTHER (1980)
The EBIT not only creates a highly charged ions, but can hold their center of mass at rest.
This overcomes the primary limitation of large HCI facilities for precision spectroscopy.
~ 1 m
To first order, the relative Doppler shift is
EBIT Internal View
EBIT on a table top
Ion production, trapping, and excitation
Intense Electron Beam (4,000 A/cm2)
Strong magnetic field (3 tesla)
Highly Charged Ions (up to Bi72+at NIST).
Ultrahigh vacuum (~10-10 torr)
Creates (by electron impact ionization) Traps (by electric and magnetic fields) Excites (electron impact)
Ion cloud width ~ 150 mm
Q up to 72+ produced
Ne-like U82+ threshold: 10 keV (10 remaining electrons)
He-like U90+ threshold: 33 keV (2 remaining electrons)
J.D. Gillaspy, Phys. Scr. T71, 99 (1997).
BLAGOJEVIC, LE BIGOT, ET AL. (2005)
KRAMIDA & READER (2006)
W III - LXXIV (~250 pages)
COMPILATIONS of W SPECTRA AND ENERGY LEVELS
KRAMIDA & SHIRAI (2006 & 2007)
IE’s SEMI-EMPIRICAL - KRAMIDA & READER (2006)
CR MODELING OF PLASMA OF W IN NIST EBIT -
RALCHENKO ET AL. (2007)
* = 2 or 3 rd order
+ = O or N
SPECTRUM OF W IN NIST EBIT AT 4228 eV RALCHENKO ET AL. (2007)
E2 LINES OF W IN NIST EBIT - RALCHENKO ET AL. (2006)
E2 AND M3 LINES OF W IN NIST EBIT
RALCHENKO ET AL. (2006)
RALCHENKO J. Phys. B: At. Mol. Opt. Phys. 40 (2007) F175