Ab initio Hartree–Fock calculations in the single-configuration approximation predict that the 3s3p6 2S1/2 level of Cl i lies far above the ionization limit, although this level is observed to be the lowest of all even J = 1/2 levels other than 3s23p44s 4P1/2, 2P1/2. The solution of this anomaly lies in configuration interaction with the high-lying portion of the 3s23p4∊d 2S1/2 continuum, which is sufficiently strong to depress the computed sp6 level to its observed position. This interaction with the continuum is an extension of the well-known interaction of spw+1 with the discrete s2pw−1 nd Rydberg series, and is important in all neutral third-row elements Al to Cl, as well as in Br and I and probably other fourth- and fifth-row elements. The effect is, however, somewhat smaller in Br i and I i than in Cl i, with the result that there exists no bromine nor iodine level that is primarily sp6 in nature. The interactions produce large changes in computed transition probabilities and photoionization cross sections.
© 1974 Optical Society of AmericaFull Article | PDF Article
Craig J. Sansonetti, Joseph Reader, A. Tauheed, and Y. N. Joshi
J. Opt. Soc. Am. B 10(1) 7-12 (1993)
Opt. Lett. 5(6) 222-224 (1980)
Robert D. Cowan
J. Opt. Soc. Am. 58(7) 924-933 (1968)