Excitation cross sections and spectroscopic classification of autoionizing levels in a caesium atom

Abstract

The electron impact excitation of the 5p 6 subshell in a caesium atom was studied by measuring the excitation cross sections of lines in ejected-electron spectra arising from the decay of the 5p 5 n 1 l 1 n 2 l 2 autoionizing doublet and quartet levels. The data were obtained for the incident electron energies ranging from the lowest excitation threshold 12.31 up to 600 eV at an observation angle of 54.7 • and with incident-electron energy resolutions of 0.2 and 0.7 eV for the near-threshold and high impact-energy regimes, respectively. Spectroscopic assignment and excitation cross sections of levels in 6s 2 , 5d6s, 6s6p and 6s6d configurations are considered.

Classification of the 5p5nln'l' LSJ energy levels of Cs excited by 30 eV electrons

“…However, the described feature applies only for these Table 2 [11] states. The same feature was observed in [13,14] for the {5d 2 ( 3 F) 4 D + 5d( 3 P)6s 2 P} 1/2 of 14.072 eV [12] and {5d( 1 P)6s 2 P + 5d( 3 D)6s 2 D} 3/2 of 14.574 eV [12] states. There are more states for which the classification of two sets of quantum numbers could be attributed.…”

“…Decrease of the intensity of some lines due to the asymmetry of the angular distribution of Auger electrons (see Table 4) was also taken into account. The suggested identification is presented in Tables 1 and 2. In the present work, the assignment of quantum numbers for 27 of 63 [12] observed states has suffered some changes compared with the identification presented in the previous works [11,13]. Assignments were given to 24 lines for the first time.…”

“…The spectra at 30 and 50 eV are rich of lines compared with that at 400 eV. Theoretical data from [11] were also used for a new assignment of the line at 14.208 eV [12] as 5p 5 6s 2 2 P 1/2 [13]. Revised identification of the experimental spectrum [12] was performed for low energy Auger lines and presented in [14].…”

Electron-Impact Excitation of the 5p55d6s2 Autoionizing States in Ba Atom

“…At present, it is difficult to say something about the spectroscopic classification of the observed resonances − ℎ, since this can be done only on the basis of the corresponding theoretical calculations. However, as shown by our theoretical studies of the excitation of the 5p 6 subshell in a neighboring cesium atom [12,13], the calculation of the near-threshold excitation of the 5p 6 subshell in barium (e.g., by using the -matrix approach) will be a very difficult task.…”

Resonance excitation of autoionizing states in alkali atoms by electron impact

“…3 позначені стрілками). Як показав теоретичний аналіз структури енергетичних рівнів, їх перерізів та часів життя, каскадний внесок в заселення АІС за рахунок радіаційних переходів не мав би перевершувати 3-4% [19,20]. Значна величина спостережуваного зростання перерізу (до 100% для натрію) та його енергетична поведінка вказують на можливу присутність тут резонансних процесів, зокрема, резонансного збудження верхніх каскадних рівнів.…”