Excitation of the lowest autoionizingnp⁵(n+1)s²,²P_3/2,1/2states of Na(n= 2), K(n= 3), Rb(n= 4) and Cs(n= 5) by electron impact

Abstract

Relativistic distorted-wave (RDW) calculations are carried out for the electron impact excitation of the lowest autoionizing states np5(n+1)s2, 2P3/2,1/2 in Na(n = 2), K(n = 3), Rb(n = 4) and Cs(n = 5) alkali atoms from the ground np6(n+1)s, 2S1/2 state. Detailed results in the range of near threshold to 1.5 keV incident electron energies are obtained for total cross sections of the magnetic substates of the individual 2P3/2 and 2P1/2 states. Utilizing these, the results are presented for their total cross sections, alignment parameter 20 of the 2P3/2 state and the intensity of the ejected electrons from the 2P3/2 state. RDW calculations excluding the exchange effect and relativistic Born approximation calculations are also performed for comparison. The results are compared and discussed in the light of earlier available results and the recently reported experimental data from the Freiburg group (Germany).

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

“…The calculation of A K for the Na [22] and K [22] state np 5 (n+1)s 2 2 P 3/2 has shown that A K was approaching zero when the energy of incoming electrons was increasing. The parameter α 2 = -1 for the np 5 (n+1)s 2 2 P 3/2 states [23]. Our calculations show that it is also equal to -1 for the J = 3 / 2 states of 5p-excited 6s 2 , 5d6s and 6s6p configurations.…”

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

“…The final excitation cross sections of lines were obtained by comparing and averaging over the energy position and the line intensity of the data from three separate measurements. The relativistic distorted-wave (RDW) cross section for the (5p 5 6s 2 ) 2 P 3/2 level [27] and the intensity ratio of lines observed in the spectrum at an impact energy of 600 eV were used for the normalization of relative experimental cross sections. After accounting for fluctuations of the experimental conditions, the total relative uncertainty was estimated as 25%.…”

“…This was performed based on both new calculations and the fact that the intensity ratio for lines 1 and 17 was 2:1. However, the calculations [13,27] show that due to the considerable relativistic effects and strong configurations mixing, the ratio of the (5p 5 6s 2 ) 2 P 3/2 and (5p 5 6s 2 ) 2 P 1/2 cross sections is far from the statistical value of 2:1 and at 400 eV the impact energy exceeds 3:1. But this value satisfies well the intensity ratio 3.6:1 of lines 1 and 18 observed in the experimental spectrum (see figure 1(b)).…”

“…Ejected-electron excitation cross sections for the 5p 5 6snl autoionizing states in the caesium atom. The dashed curve presents the cross section for the (6s 2 ) 2 P 3/2 level calculated in the RDW approach [27].…”

Theoretical study of 4p5nln'l'LSJstates of Sr ion excited by electron impact on Sr atom

“…Moreover, in the case of core excited states of alkali atoms, only one Auger decay channel is possible [23,24], therefore B(αLSJ, J f ) = 1.…”