Spin-resolved Auger electron spectroscopy of barium atoms

Kuntze, Richard A.; Salzmann, Michael; Böwering, N.; Heinzmann, Ulrich

doi:10.1103/physrevlett.70.3716

Cited by 35 publications

(29 citation statements)

References 25 publications

(30 reference statements)

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“…Recently, these Auger electrons have been measured to be strongly spin polarized for the electron spectroscopy studies with free barium atoms [1] and Rb-adsorbates [2], where the primary photoemission process has been performed by means of spin polarized i.e. circularly polarized radiation.…”

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confidence: 99%

“…Consequently, an orientation of the intermediate state can be transferred partially to the Auger electron spin polarization [5,6]. On the other hand the data of spinand angle resolved Auger spectroscopy can be used to determine alignment and orientation of the intermediate photoion state from the experiment [ 1 ]. Cross comparison of these results with the corresponding dynamical parameters characterizing the primary photoelectron emission process, angular distribution and spin polarization parameters which form a "complete experiment", should answer whether photoelectron and Auger electron emission are subsequent processes in a two-step model or whether they have to be seen as a dynamical combination.…”

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“…A reference case is the 4 d ionization of xenon [7] for which both the occurrence [8] and the vanishing [9] of postcollision interaction was discussed in detail. kinetic energy corresponding to a p;-1 hole state [ 1 ] to include the simultaneous detection of the corresponding photoelectrons and their spin polarization. It is the purpose of this publication to present these data obtained with circularly polarized photons at energies around 28 eV and to compare the spin polarization values of Augerand photoelectrons measured.…”

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Spin polarization of Auger- and of photoelectrons from barium atoms exposed to circularly polarized radiation and their cross comparison

Kuntze

Salzmann

Böwering

et al. 1994

Z Phys D - Atoms, Molecules and Clusters

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Abstract.New results of spin polarization of both photoelectrons and Auger electrons are reported after 5p photoionization of free Ba atoms with circularly polarized light. A substantial polarization transfer from the spin polarized photons to the spin polarized photoelectrons and via the hole state orientation to the spin polarized Auger-electrons is observed. The cross comparison of the results for photoelectrons and Auger-electrons allows a quantitative test of the assumed two step model where both electron-emission processes occur in sequence. 32.80.Hd Creation of vacancies in inner atomic shells by photon or particle impact often gives rise to subsequent Auger decay. Recently, these Auger electrons have been measured to be strongly spin polarized for the electron spectroscopy studies with free barium atoms [1] and Rb-adsorbates [2], where the primary photoemission process has been performed by means of spin polarized i.e. circularly polarized radiation. In their emission characteristics these Auger electrons reflect a non-statistical population of the magnetic substates of the intermediate ionic state produced by the spin oriented initial impact [3,4]. Consequently, an orientation of the intermediate state can be transferred partially to the Auger electron spin polarization [5,6]. On the other hand the data of spinand angle resolved Auger spectroscopy can be used to determine alignment and orientation of the intermediate photoion state from the experiment [ 1 ]. Cross comparison of these results with the corresponding dynamical parameters characterizing the primary photoelectron emission process, angular distribution and spin polarization parameters which form a "complete experiment", should answer whether photoelectron and Auger electron emission are subsequent processes in a two-step model or whether they have to be seen as a dynamical combi-

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Spin polarization of Auger- and of photoelectrons from barium atoms exposed to circularly polarized radiation and their cross comparison

Kuntze

Salzmann

Böwering

et al. 1994

Z Phys D - Atoms, Molecules and Clusters

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“…Although Auger spectroscopy is a well established field of intense research activity in gas phase, surface and solid state physics, it is nearly solely concerned with the Auger intensities. A few studies have yielded phase-shift-dependent information such as angular distribution parameters, i.e., [3][4][5], or spin polarization parameters [6,7], but, as these experiments probed polarization terms depending on the cosine of the relative phases, they can be compared to angular distribution measurements in photoionization and, hence, their sensitivity to the phase shifts is not very high.…”

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Dynamically Induced Spin Polarization of Resonant Auger Electrons

et al. 1999

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Resonant Auger electrons from the decay of the atomic Xe 4d 21 5͞2 6p͑J 1͒ state excited with linearly polarized light are shown to have a strong spin polarization. The core hole states are not oriented in this case. We found polarization values ranging from 20.46 to 0.57. For the decay to the 5p 4 ͑ 1 D 2 ͒6p͑ 2 P 1͞2 ͒ state the ratio of the radiationless decay matrix elements and their relative phase, including its sign, are derived. [S0031-9007(99)09447-8]

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“…Spin-dependent effects have been investigated experimentally in most cases with ferromagnetic material [2,3], where the electrons to be emitted are highly spin oriented in the ground state. Very recently first experimental results of spin dependent Auger emission from non-magnetic Rb-layers [4] as well as from free unoriented Ba-atoms [5] exposed to circularly polarized radiation have been reported. The spin polarized radiation creates spin polarized primary photoelectrons and thus spin oriented hole states whose decay results in spin polarized Auger electrons.…”

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Angle and spin resolved Auger and photoelectron spectroscopy on Rb-layers by means of circularly polarized VUV radiation

Stoppmanns

David

Müller

et al. 1994

Z Phys D - Atoms, Molecules and Clusters

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Abstract. Normal incidence circularly polarized VUV radiation with energies around 23 eV creates spin polarized photoelectrons from thick layers of Rb on Pt(ll 1) and thus excites oriented 4p hole states. The preferential spin direction of the Auger electrons and its dependence upon the emission angle has been measured and is compared with the corresponding angular dependence of the primary photoelectron spin polarization also measured. Since the CVV Auger decay relates to a s a pair of valence electrons, the cross comparison of results for photoelectrons and Auger electrons studies the questions on whether photoemission and Auger decay Occur in sequence, assuming an independent two step model, and whether the valence s-electrons couple to a singlet state configuration. PACS:79.20.Fv; 79.60.Bm a singlet state configuration or also partially to a triplet state configuration. Figure 1 shows the spin polarization of the Auger electrons averaged across the Auger peak measured [4] at rubidum thick layers on Pt(111) in normal emission versus the energy of the exciting circularly polarized VUVradiation in normal incidence, after having subtracted the unpolarized inelastic background in the spin-resolved Auger electron spectra. Figure 1 also denotes the thresholds for p_~ and pa hole creation by the photons. The p½ hole states excitect above the p± threshold decay via a Koster-Kronig transition into p] hole states [6,7]. Since 2 * • at higher photon energies phototransltlons into d states are more probable, the creation ofp~ holes with magnetic sublevels mj = +½ and ms = +~ Is preferred against creation of p~ holes with ms = -½ and rn; = -3, resultPhoton impact on solids often creates core level holes with subsequent valence electron Auger decay. In Auger spectroscopy usually the energetic position and the shape of Auger lines in spin-independent intensity spectra are studied [ 1 ]. Spin-dependent effects have been investigated experimentally in most cases with ferromagnetic material [2,3], where the electrons to be emitted are highly spin oriented in the ground state. Very recently first experimental results of spin dependent Auger emission from non-magnetic Rb-layers [4] as well as from free unoriented Ba-atoms [5] exposed to circularly polarized radiation have been reported. The spin polarized radiation creates spin polarized primary photoelectrons and thus spin oriented hole states whose decay results in spin polarized Auger electrons. It is worth noting that the Auger electrons from the CVV decay of metallic Rb-layers could not be observed for an isolated Rb atom since the alkalis only have one outermost s electron. The second s electron for the decay has to be supplied in the condensed matter by the Rb neighbours via the joint valence band. This gives rise to the question on whether they only couple to

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Spin-resolved Auger electron spectroscopy of barium atoms

Cited by 35 publications

References 25 publications

Spin polarization of Auger- and of photoelectrons from barium atoms exposed to circularly polarized radiation and their cross comparison

Spin polarization of Auger- and of photoelectrons from barium atoms exposed to circularly polarized radiation and their cross comparison

Dynamically Induced Spin Polarization of Resonant Auger Electrons

Angle and spin resolved Auger and photoelectron spectroscopy on Rb-layers by means of circularly polarized VUV radiation

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