The 5dnp and 5dnf J=1 autoionizing series of Ba in one-photon laser excitation from the 6s²¹S₀ground state

Abstract

The Sdnp, n f 3 = 1 series of barium converging ! o both !he 5d,,, and Sd,,, limits were studied in a heat-pipe system in a one-step pulsed uv laser excitation from the atomic ground state. Strong interscries and continuum interactions were observed and experimental evidence of interaction with 6p7s J = I levels was found. A comparison of the observed defect method is presented. The agreement is satisfactory in view of the complexity of the calculations. spmr?. with rPPc!ra ca!a.!atPd 8" cigc"chmne!

Absolute photoionization cross sections of the Ba ground state in the autoionization region: I. 238 - 218 nm

“…0953-4075/97/143159+13$19.50 c 1997 IOP Publishing Ltd Some noteworthy investigations have also been reported in the 1990s. Gounand et al (1991) observed 5dn J = 1 o autoionizing series using a multistep laser excitation technique, whereas Abutaleb et al (1991) observed the same autoionizing series using onephoton laser excitation from the ground state. The bandwidths were 0.0035 nm and 0.0025 nm for the former and latter experiments, respectively.…”

“…Since we used the same theoretical procedures as those described in several other papers (see, for example, Aymar 1991, Aymar et al 1996) only a brief description is given here, mainly concerning the variational basis used in the R-matrix calculation. Most of the previous eigenchannel R-matrix calculations devoted to the odd-parity J = 1 spectrum of Ba (Aymar 1990, Gounand et al 1991, Abutaleb et al 1991 incorporated spin-orbit effects by combining R-matrix calculations in LS-coupling with the jj -LS frame transformation. This work, as in the previous study performed by Greene and Aymar (1991), uses the jj -coupled eigenchannel R-matrix, where spin-orbit effects are explicitly taken into account within the R-matrix reaction volume.…”

“…The variational basis consists of 1326 closed-type basis functions and 39 open-type basis functions. Note that to improve the convergence of the variational calculation we use a larger set of variational basis functions than in the previous R-matrix calculations dealing with the Ba photoabsorption spectrum (Aymar 1990, Greene and Aymar 1991, Gounand et al 1991, Abutaleb et al 1991.…”

4fnfdoubly excited autoionizing series in barium

“…From Sd 'G4 we selectively excited the single J =5 and the two J=4 Sd&/2nf states up to n =34 with a few exceptions where the Sd3/2nf series are perturbed by members of the Sd5/2nf and/or 5d5/2np series [9]. Also, Sd~/2nf J =4 states for n = 17,20,21,25,40 It illustrates that many of the 5d 3/z n f J states can be used for selective further excitation. The use of various intermediate Sd3/znf J states provides a wealth of information on the final 4fnf states.…”

“…2 is unexpected as, in general, 6J = -1 transitions are weak in excitation of 5dnf from 5d states. The oscillator strength for excitation of these series in between n = 2 1 -23 is enhanced by [19,20]. The data on the 5dnf multiplet were used in a Slater-Condon analysis of the configuration in terms of direct and exchange electrostatic interactions [21].…”