WORKING GROUP 2: ATOMIC TRANSITION PROBABILITIES

W. L. WIESE, Chair
National Institute of Standards and Technology
Physics Building, Room A267
Gaithersburg, MD 20899

The Data Center on Atomic Transition Probabilities at the National Institute of Standards and Technology (NIST) Gaithersburg, MD 20899, USA is continuing its critical data compilation work and is also participating in the development of a comprehensive atomic spectroscopic database of which a first version is installed on the World Wide Web. This database may be accessed from the NIST Physics Laboratory WWW homepage at http://physics.nist.gov/. Further details on this and several other atomic spectroscopic databases on the Internet are given in the report of Working Group 1.

The comprehensive NIST bibliographical database, which now contains more than 6,600 entries, has been updated through June 1996 and is also available at the above cited World Wide Web site.

The current compilation work of the NIST atomic transition probabilities data center is centered on the evaluation and tabulation of numerical data for the lighter elements. Work is in progress on hydrogen, helium, lithium, beryllium, boron, fluorine, neon, sodium, and magnesium. The tabulations include allowed (electric dipole) as well as forbidden (mainly magnetic dipole and electric quadrupole) lines.

Some major works on transition probability and lifetime data during the last three years are the following:

(a) In early 1996, the NIST data center published a 532-page volume of critically evaluated transition probabilities for the three elements carbon, nitrogen and oxygen as Monograph No. 7 of the Journal of Physical and Chemical Reference Data. This volume contains about 12,500 transitions for all 21 spectra of these three elements.

(b) A large amount of data resulting from the Opacity Project and its successor, the Iron Project, has been published. For example, very extensive sophisticated calculations of transition probabilities for various ions of iron [4,69,75,76,78,87] have been undertaken.

(c) Systematic and accurate multi-configuration calculations of transition probability data have been undertaken by a group of theoreticians under the leadership of Froese Fischer, Hibbert, and Brage (members of the SAM-project). This group maintains a World Wide Web site
(address: http://aniara.gsfc.nasa.gov/sam/sam.html) from which new results are available.

(d) A large review concerned with data for lines starting from the ground states of many atoms and ions has been published by Verner et al. [102] Their listings contain 2,249 spectral lines, and the data are drawn mostly from the Opacity Project and recent critical compilations.

(e) Another review of neutral line oscillator strengths has been published by Doidge [34]. This compendium contains oscillator strengths for neutral atomic resonance lines of 65 elements and has been collected mostly for the needs of laboratory atomic absorption spectroscopy.

(f) A new edition of ``Astrophysical Quantities" prepared by Cowley et al. [31], contains oscillator strength tables for about 500 prominent lines of astrophysical interest.

(g) Finally, it is of interest to note that a number of informative review articles on the status and accuracy of oscillator strength data were given at the 5th International Colloquium on Atomic Spectra and Oscillator Strengths for Astrophysical and Laboratory Plasmas, the proceedings of which are in preparation (see Tchang-Brillet [98]).

The remaining part of this report is a bibliography of selected recent literature references which contain new transition probability data of astrophysical interest produced during the last three-year period. Thus, this new selected bibliography continues where the last working group report left off. As in the previous reports, the bibliographical material is ordered with respect to element and state of ionization. Table 1 provides an overview of the bibliographical data by spectrum. The references are identified by a running number which refers to the general reference list at the end of this report. In the general reference list the literature is ordered alphabetically according to first author, and each reference contains one or more code letters indicating the method applied by the authors. These code letters are defined as follows:

• THEORETICAL METHODS:
• EXPERIMENTAL METHODS:
• References WG2
• Important Literature References