Measurement of the absolute 4d-photoabsorption cross section of atomic barium

Abstract

The absolute photoabsorption cross section of atomic barium in the region of the 4d-giant resonance (80-140 eV) has been determined. The vapour density in the absorbing metal vapour column, required for the determination of the absolute cross sections was measured quasi-simultaneously with the absorption using a Mach-Zehnder interferometer. Our data show good agreement in terms of spectral signature with existing relative photoabsorption measurements. The measured absolute cross section corroborates the results of recent many-body calculations.

Photoionization cross sections of atomic ions from merged-beam experiments

“…Lucatorto et al [61], von dem Borne et al [62] Ba + Kjeldsen et al [59], Lucatorto et al [61], Lyon et al [63] Ba 2+ Kjeldsen et al [59], Lucatorto et al [61], Bizau et al [64] Ba 3+ Bizau et al [64] La + Kjeldsen et al [65] La 3+ Kjeldsen et al [66] Ce 4+ Kjeldsen et al [66] The spectral resolution that can be obtained depends on a number of factors, in particular the properties of the target ion and the photon source. In favourable cases a resolution close to 1 meV (see, e.g., [43]) can be obtained utilizing a high-performance synchrotron-radiation beam line, such as beam line 10.0.1 at the ALS.…”

“…Although many different kinds of experiments dealing with 4d excitation have been carried out there has until recently been a distinct lack of absolute photoionization cross sections. For a long time such data were only available for Xe (see [4,[131][132][133][134][135], and references therein) and Ba-Ba 2+ [61,62], but with the advent of undulator-based merged-beam measurements this situation has been improved. Thus, new absolute photoionization cross sections have been measured for Te − , I − , I + , I 2+ , Xe + -Xe 6+ , Cs + , Ba + -Ba 3+ , La + , La 3+ and Ce 4+ , as listed in table 1.…”

Experimental study of 4f wavefunction contraction: 4d-photoionization of low-charged ions of I, Xe, Cs and Ba

“…The experimental data available are mainly relative cross sections and identifications of spectral features resulting from the excitation of autoionizing resonances. However, for quantitative conclusions absolute cross sections or total oscillator strengths are also needed, but no quantitative data are available for these elements except for the Xe atom, where photoabsorption and decay have been studied for more than 30 years (see [1][2][3][4][5][6] and references therein) and for the Ba spectra [7][8][9] discussed below.…”

Photoionization of atomic Ba in the region of the $5p \rightarrow {n}_{1}{{\ell }}_{1}{n}_{2}{{\ell }}_{2}{n}_{3}{{\ell }}_{3}$ excitations

“…Experimental investigations involving electron impact ionization [1][2][3], photoion and photoabsorption spectroscopy [4][5][6][7][8][9][10][11][12][13][14] and photoelectron spectroscopy [15][16][17][18][19][20][21][22] of atomic barium as well as complementary theoretical studies [3,[22][23][24][25][26][27] have attracted an on going interest since some of the first measurements involving Ba + and Ba 2+ ion yields made with a He I radiation light source [4] more than 40 years ago. From an experimental perspective, production of an atomic beam to carry out quality measurements is not excessively demanding as the minimum temperature required to produce a suitable vapor pressure is on the order of about 600 °C [28].…”