The angle-resolved Kr L_2,3M_4,5M_4,5Auger multiplet following proton impact ionization

Abstract

The angle-resolved Kr L2,3M4,5M4,5 Auger spectra induced by proton impact ionization were measured at 1, 2.6 and 3.6 MeV proton energies where high-resolution spectroscopy techniques have been applied. The Auger energies and relative line intensities are compared with different earlier experimental data as well as our numerical results which have been obtained within a multiconfigurational Dirac-Fock approach. The alignment parameter 20 of the singly ionized krypton atoms has been extracted from the experimentally accessible anisotropy parameter A2 applying a special method, using the theoretical values of the angular distribution parameter 2 .

Variation in resonant Auger yields into the1G4sdotnlstates of Kr across the L3threshold

“…The observation of the 1 G 4 decay in the present study has shown that the angular distribution is close to isotropic; the absolute value of the anisotropy parameter is lower than 0.1. A previous calculation predicts that the parameter is -0.045 [22].…”

“…In addition, in the energy range of interest the normal Auger peaks are distorted through the post-collision interaction (PCI), and these peaks can be approximated with the following equation [10,22,[33][34][35][36]:…”

“…Photoabsorption spectrum of Kr 2p electrons was observed by some researchers and the excited states with higher principal quantum numbers were reported [17][18][19]. Normal Auger electron spectra using charged-particle techniques were observed and analyzed, which showed that the 1 G 4 final state yields the strongest peak in the electron kinetic-energy region near 1460 eV [20][21][22]. The resonant Auger transitions were found from the 2p -1 nl states by the present authors, who used monochromatized undulator radiation combined with the grating monochromator having high resolving power [23,24].…”

Resonant Auger spectrum following Kr:2p → 5s photoexcitation

“…The Kr:LMM normal Auger spectra following photoionization were also observed for the first time in this study and will be reported in detail elsewhere. Spectra following electron and proton impact ionization in the vapour phase (Krause 1965, Siegbahn et al 1969, Werme et al 1972, Aksela et al 1980, Levin et al 1986, Kleiman et al 1999 and in solid samples (Baba et al 1992, Marton et al 1993 were reported previously. Baba et al (1992) used an aluminium-Kα line source (1486 eV), and thus their assignment is questionable.…”

“…The Kr:2p electron can be photoexcited into the 5s orbital (Wuilleumier 1971, Schmelz et al 1995, but there is no report of electron emission associated with Auger transitions from the Kr:2p −1 5s state. Further, although normal Auger electron spectra from Kr:2p −1 states were measured following electron-beam and proton-beam excitation (Krause 1965, Siegbahn et al 1969, Werme et al 1972, Aksela et al 1980, Levin et al 1986, Kleiman et al 1999, normal Auger electron emission from Kr:2p −1 states using x-ray excitation has not yet been studied in the vapour phase. The lack of data for the Kr:2p −1 state may be due to the difficulty of using a bright photon source that can supply, with a high resolution, photons of about 1700 eV, required to produce the Kr:2p −1 states.…”