Spectroscopic Research Projects on Heavy Elements at NIST

1. Spectroscopic Research Projects on Heavy Elements at NIST Wolfgang L. Wiese National Institute of Standards and Technology (NIST), USA

2. Participants Experimental Research: J. Reader, G. Nave, J. Gillaspy, J. Pomeroy Theoretical Approaches: Ch. Froese-Fischer,* Y. Ralchenko,* Y.-K. Kim, * P. Stone* Data Assessment and J. Reader, E. Saloman, Compilations: J. Fuhr, D. Kelleher,* L. Podobedova,* A. Kramida,* W. Wiese* Database Development: Y. Ralchenko,* __________ A. Kramida* *indicates Contractors or Guest Researchers

3. Some On-going Spectroscopic Research Projects on Heavy Elements at NIST • Experimental observations of the spectra of highly charged tungsten ions, in the range from W+35 to W+50, with an Electron Beam Ion Trap (EBIT) and their analysis. • Calculations of ionization and excitation cross-sections of neutral and singly ionized Mo and W with the Binary-Encounter-Bethe (BEB) model. • An updated and expanded critical compilation of spectroscopic reference data, focusing on better transition probabilities, for Fe I and Fe II.

4. The NIST Electron Beam Ion Trap (EBIT) EBIT not only creates a HCIs, but can holds their center of mass at rest. This overcomes the primary limitation of large HCI facilities for precision spectroscopy. To first order, the relative Doppler shift is Dl/l =v/c EBIT size ~ 1 m

5. A simplified EBIT: Intense Electron Beam (4,000 A/cm2) Strong magnetic field (3 tesla) Highly Charged Ions (up to Bi72+at NIST). 2 cm Ultrahigh vacuum (~10-10 torr) Creates (by electron impact ionization) Traps (by electric and magnetic fields) Excites (electron impact) Ion cloud width ~ 150 mm

6. Quantum Microcalorimeter • operates at 65 mK • absorber: a foil of • superconducting tin • thermistor: neutron • transmutation-doped • (NTD)germanium

7. The “Pre-microcalorimeter Compromise” SiLi Crystal

8. “Crystal-quality” resolution, wide bandwidth and 100% efficiency. Ar L-shell K-shell

11. Some On-going Spectroscopic Research Projects on Heavy Elements at NIST • Experimental observations of the spectra of highly charged tungsten ions, in the range from W+35 to W+50, with an Electron Beam Ion Trap (EBIT) and their analysis. • Calculations of ionization and excitation cross-sections of neutral and singly ionized Mo and W with the Binary-Encounter-Bethe (BEB) model. • An updated and expanded critical compilation of spectroscopic reference data, focusing on better transition probabilities, for Fe I and Fe II.

13. Electron-Impact Cross Section Database(http://physics.nist.gov/ionxsec)M. A. Ali, K. K. Irikura, Y.-K. Kim, P. M. Stone 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, 2006: 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

16. Some On-going Spectroscopic Research Projects on Heavy Elements at NIST • Experimental observations of the spectra of highly charged tungsten ions, in the range from W+35 to W+50, with an Electron Beam Ion Trap (EBIT) and their analysis. • Calculations of ionization and excitation cross-sections of neutral and singly ionized Mo and W with the Binary-Encounter-Bethe (BEB) model. • An updated and expanded critical compilation of spectroscopic reference data, focusing on better transition probabilities, for Fe I and Fe II.

17. Fe I

18. Fe I

19. Fe II

20. Fe II

21. Fe I 2006 1988

22. Fe II 2006 1988