References and Notes for Boron ( B )

BTG74 C. M. Brown, S. G. Tilford, and M. L. Ginter, J. Opt. Soc. Am. 64, 877 (1974).
EL01 R. Engleman, Jr. and U. Litzén, unpublished data (2001). Engleman and Litzén improved and extended the infrared observations of B I and also made new measurements of several ultraviolet lines. The new infrared wavelengths and resulting level values supersede the data in [L70b].
EOHJ70 B. Edlén, A. Ölme, G. Herzberg, and J. W. C. Johns, J. Opt. Soc. Am. 60, 889 (1970).
FW96 J. R. Fuhr and W. L. Wiese, NIST Atomic Transition Probability Tables, CRC Handbook of Chemistry & Physics, 77th Edition, D. R. Lide, Ed., CRC Press, Inc., Boca Raton, FL (1996).
GF02 W. L. Glab and A. M. Falleur, J. Quant. Spectrosc. Rad. Trans. 73, 121 (2002).
GM62 P. Gunnwald and L. Minnhagen, Ark. Fys. 22, 327 (1962).
GV72 D. Goorvitch and F. P. J. Valero, Astrophys. J. 171, 643 (1972).
JLKK93 S. G. Johansson, U. Litzén, J. Kasten, and M. Kock, Astrophys. J. 403, L25 (1993). The wavelengths of transitions involving the B I 2s22p, 2s23s, and 2s2p2 2D levels are given separately for the 11B and 10B isotopes in this reference. Weighted average wavelengths are given here for these lines, with the two isotopic wavelengths for each transition being weighted according to the relative abundances. Combination of the measurements of the 2s22p 2P - 2s2p2 2D lines [JLKK93] with the isotopic ionization-energy shift obtained for the 2s2p2 2D term by Edlén, et al. [EOHJ70] shows that the isotopically weighted average ionization energy for each of the 2s22p 2P ground-configuration levels probably differs by less than 0.01 cm-1 from the ionization energy of the corresponding level of the dominant 11B isotope. The values of the two 2s22p 2P levels given in [JLKK93] (based on a value 0.000 cm-1 for the 2P1/2 level of each isotope) are thus taken as equal to isotopically averaged values. The isotopically averaged values of the higher levels were obtained by using the averaged wavenumbers of the lines. Any additional error introduced by this procedure should be smaller than 0.01 cm-1. It should be noted that the separations of the two isotopic components of the lines (which range from 0.011 to 0.025 Å) are large relative to the uncertainties of the individual measurements (less than 0.001 Å).
L70b U. Litzén, Phys. Scr. 1, 251 (1970).
LZJK98 U. Litzén, T. Zethson, P. Jönsson, J. Kasten, R. Kling, and F. Launay, Phys. Rev. A 57, 2477 (1998). The authors measured two isotopic components for each B II transition involving the 2s2, 2s2p, and 2p2 levels, the observed 10B/11B splittings being in the range 0.42 to 0.89 cm-1. The wavelengths given here are isotopically weighted averages. We also give weighted averages for the corresponding energy levels. Although we have retained two decimal places for the levels, the user should keep in mind the relatively large isotopic splittings.
M03 D. C. Morton, Astrophys. J. Suppl. Ser. 149, 205 (2003).
O70 A. Ölme, Phys. Scr. 1, 256 (1970).
OL92 T. R. O'Brian and J. E. Lawler, Astron. Astrophys. 255, 420 (1992).
R02 A. N. Ryabtsev, private communication (2002). Ryabtsev obtained a value of 66928.04(3) cm-1 for the 11B I ionization energy by adjusting the experimental value of Glab and Falleur [GF02] to a more accurate value for the 11B I 2s23s level [JLKK93]. We quote this adjusted 11B value as the most accurate estimate of the isotopically averaged B I ionization energy (see our note appended to [JLKK93]). With an appropriate adjustment, the value obtained by Edlén et al. [EOHJ70] for the center-of-gravity ionization energy was 66928.15(10) cm-1.
R98 A. N. Ryabtsev, private communication (1998). Ryabtsev has reevaluated the B II levels using all available data. Since no transition between singlet and triplet levels has been observed, he followed Ölme [O70] in fixing the triplet system relative to the singlets by assuming that the 2s6g 1G and 3G levels have the same value relative to the ground level. The new level values then required a lowering of the basic 2s2p 3P° and 2p2 3P levels by 0.5 cm-1 from their previous values. We have lowered Ölme's value for the B II ionization energy by 0.4 cm-1 based on Ryabtsev's new values for the 2s5g and 2s6g levels used by Ölme. The uncertainties of the singlet-triplet connection and of the ionization energy are both probably of the order of 1.0 cm-1.
RT76 R. A. Roig and G. Tondello, J. Phys. B 9, 2373 (1976). The quantity "x" represents an uncertain correction for the B I 2s2p2 4P term. The estimated value of "x" is 0.0 ±15 cm-1.