THE HIGH ENERGY EXCITED SHAKE-UP ELECTRON SPECTRA OF KRYPTON

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THE HIGH ENERGY EXCITED SHAKE-UP ELECTRON SPECTRA OF KRYPTON

B. Eriksson, S. Svensson, N. Mårtensson, U. Gelius

To cite this version:

B. Eriksson, S. Svensson, N. Mårtensson, U. Gelius. THE HIGH ENERGY EXCITED SHAKE-UP

ELECTRON SPECTRA OF KRYPTON. Journal de Physique Colloques, 1987, 48 (C9), pp.C9-531-

C9-534. �10.1051/jphyscol:1987987�. �jpa-00227408�

THE HIGH ENERGY EXCITED SHAKE-UP ELECTRON SPECTRA OF KRYPTON

B. ERIKSSON, S. SVENSSON, N. MARTENSSON and U. GELIUS

Department of Physics, Uppsala University, PO Box 530, S-751 21 Uppsala, Sweden

The Kr3p and Kr3d core level shake-up spectra have bcen studied using monochromatized X-ray photoelectron spectroscopy (XPS). The spcctra show interesting differences which can be explained by intermediate coupling calculations. In the KT 3p shake-up spectrum the spin-orbit splitting of the 3p core level dominates. However a rich Iinc structure , due to correlation effects

.

Core electron shake-up spectra froni closed- shell atoms have been studied for almost two decades. These spectra have been found to be valuable for tests of various theoretical methods and models. So far it has been sufficient for the assignment of the spectra to include only the effect of the term splitting of the various shake-up configuration series.

Relativistic effects have been taken into ac- count in a limited way by considering the spin-or-bit splitting of the core level and superimposing this splitting on all the valence excited states.

In this work the core-electron shake-up spectra associated with the Kr3p and Kr3d subshells have been studied using mono- chromatized high energy excited(l487eV photon energy) XPS. The enhanced reso- lution obtained in a monochromatized photo- electron spectrum reveals a more complex structure than has been previoudy reported 11.21. T h e earlier results could be satisfactorily described by simply calculating the average energy for the different final state configur~tions.1~contrast to this the assign- ment of the high resolution spectra has to be

Binding energy (eV) (rel. 3d5,J

Fig.1 The Kr3d shake-up spectrum.

he structures 1-12 can be assigned to

!he 3d94p5np and 13-14 to the 3d94s5s configurations.

A In

.-

e

- _d

.- 0

In C C Q)

C 1 1 13

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I I I

46.0 36.0 26.0 16.0

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Kr 3d shake-up

1

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1987987

C9-532 JOURNAL DE PHYSIQUE made using intermediate coupling. The spin-

orbit splitting is much larger for the Kr3p than i n the case of the Kr3d level. As a consequence the shake-up specna show an interesting difference. The main features of the Kr 3p shake-up spectrum can be described by spin-orbit doublets of roughly the same relative intensity ratio and spin orbit splitting as the main line. In the case of the Kr 3d spectrum the term splitting is of the same magnitude as the spin-orbit splitting and an assignment has to be made by taking intermediate coupling into account.

The spectra were recorded using our electrostatic ESCA instrument which is provided with an AIKa crystal monochro- mator. The pressure in the sample compartment was held at such a low pressure that the inelastic scattering contribution to the spectra could be neglected.

The Kr3d shake-up spectrum is shown in Fig. 1. A large number of structures can be seen, which are numbered in order of increasing binding energy. In order to make a preliminary assignment of the satellite spectrum we have calculated shake-up energies using the relativistic MCSCF program by Grant et a1.131. Calculations were made for the 3d94p5np and the 3d94sns- configurations, with n=5, 6 and 7. The calculated shake-up energies are given in table 1 .The effect of correlation was included in an approximate way by simply shifting the calculated energies so that the energy of the Kr4p312 and Kr 4s core holes takes the experimental values. This shift is approximately 1 eV for the Kr4p312 core hole. For the Kr4s core hole this shift is approximately 3eV.

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Binding energy (eV) @el. 3p3,*)

Fig.2 The Kr3p shake-up spectrum. The main structures are interpreted as originating from the 3p54p55p wrfiguration.

The fine structures arc also due to electron correlation.

Calculated Sd^pSSp-energies (rel.3d5/2)(eV)

( l D²) 5 p^{1 /}2²D^{3 /}2 ( l D2) 5 p 3 / 22D5 / 2

(1D2)5pi/2 2D5/2 (1D2) 5P3/22D3 /2 (3D3)5p1 / 2 2D5 / 2

(3D3)5p3/2 2D3/2 (3D3)5p3/2 2D5/2 (³F⁴)5p3/2 ²D⁵/2 (3Di)5pi/2 2D3 / 2

(3D2)5pi/2 2D3/2 (3D l ) 5 p3/2 2D3 /2 (3D²)5pi/2 ²D5/2 ( 3 D2) 5 P3 /2 2D5 / 2

(3D2)5p3/2 2D3 / 2

(3F3)5p3/2 2 D3 / 2 ( 3 D I ) 5P 3 / 2 2D5 /2 (3F3)5p3/2 2D5/2 ( 3 F3) 5 p i / 22D5 / 2

(3F2)5pi/22D3/2 (3p1)5p3/22D3 / 2

(³Pl)5pi/2²D3/2 (³F²)5p³/^{2 2}D^{5 / 2} (³F²)5p³/^{2 2}D³/2 (3F2)5pi/2 2D5 / 2

(3Pl)SP3/22D5/2 (3P0)5P3/2 2D3/2 (3P2)5pi/22D5/2 (1F3)5P3/2 2D5/2 (3p2)5pi/2 2D3 / 2

(3p2)5p3 / 2 2D3 / 2

(¹F3)5pi/^{2 2}Ds/2 (³P2)5p3/2 ²D5/2 ('F3)5P3/2 2&3/2 ('Pl)5P3/22D3/2

(1P\)5P3P.2D5/2

( l P l ) 5P 1 /22D3 / 2

17.13 17.26 17.43 17.43 17.53 17.59 17.75 8.11 18.30 18.36 18.50 18.53 18.56 18.66 18.71 18.72 18.80 18.97 19.00 19.08 19.14 19.21 19.26 19.29 19.37 19.56 19.72 19.80 19.81 19.83 19.95 19.98 20.28 20.73 20.81 20.93

Calculated 3d'4s5s energies (rel. 3d5/2)(eV)

( 3 D3) 5 s2D5 / 2

(3D2)5s2D3 / 2 ( 3 D2) 5 S2D5 / 2

(3D I ) 5 S2D 3 / 2

( l D2) 5 s2D5 / 2 ( 1 D 2 ) 5 S2D3 / 2

35.15 35.35 35.80 36.40 36.69 37.19

Calculated 3ps4p5Sp-energies (rel.3p3/2)(eV)

OP^VW^W.

O-vtfvm^w

(xP\)5pm2pm

0P\)5P3/22P\P.

(3D3)5p3/22P3/2 (³D²)5pi/^{2 2}P3/2 (³D²)5p3/2²Pl/2 (³D2)5p3/2²P3/2 (3D i ) 5 p i / 22P i / 2 (3Di)5pi/22P3/2 (3P2)5p3/22Pl/2 (³Di)5p³/2²P3/2 (3D l ) 5 p 3 / 22 pl / 2 (3P2)5p3/22P3/2 (3p2)5pi/22P3/2 (3P0)5pi/22Pl/2 (3P0)5p3/22P3/2 (3S l ) 5 p i / 22P l / 2 (3Sl)5p3/22P3/2 (3Si)5pi/22P3/2 (³Pl)5pi/2²P3/2 (³Sl)5p3/2²Pl/2 (3Pl)5p3/22P3/2 (3Pl)5p3/22Pl/2 (1D2)5p3/22 p3/2 (3P l ) 5 p i / 22P l / 2 (¹r>2)5pi/2 ²P3/2 (¹D2)5p3/2²Pl/2 (1S0)5P3/2,1/22P

17.48 17.52 17.67 17.91 18.36 18.79 18.94 19.07 19.39 19.45 19.60 19.61 19.69 19.82 20.08 20.45 20.56 26.24 26.41 26.63 26.77 26.85 26.90 26.94 26.98 26.99 27.13 27.73 29.04

Table 1. Calculation of energies of shake-up states in an intermediate coupling scheme.

C9-534 JOURNAL DE PHYSIQUE Structures number 1-12 can possibly be

assigned to the 3d94p5np-configurations.

The two structures 13 and 14 are more straightforward to interprete. We conclude that they originate from the 3d94s5s

-

configuration, because of both position and shape.We assign the 3d94s(3D3)5s 2 ~ 5 1 2 and the 3d94s(3D2)5s 2D3/2 to structure 13.

The rest of the 3d94s5s-configuration can possibly explain structure 14.

The Kr3p shake-up spectrum, shown in Fig.2, differs substantially from the Kr3d spectrum. One reason for this is that the Kr3p core hole state itself is influenced by strong interactions of super Coster-Kronig type involving the 3&nl and 3& &I- con- figurations 141. This interaction gives rise to a complicatedline shape with a number of satellite lines and to a substantial correlation energy shift of the main lines. However, if these correlation effects are neglected, the intermediate coupling calculations give a result which is rather close to a spin-orbit doublet picture. The Kr3p shake-up spectrum thus consists mainly of two peaks. These two peaks seem to originate from the Kr3p312 and the Kr3pl/2 core holes,respec- tively. In this respect they resemble the Hg4f(6s-ns) /5/ and the Xe3d(5p-np) 161 shake-up spectra. Thus to a first app- roximation we have neglected the correlation satellites and calculated the 3p54p5np-confi- gurations, which are given in Table 1.As above, we roughly approximate the correlation effects by just shifting the calculated energies so that the experimental and theoretical values of the Kr3p3/2 core hole coincide.This shift of -2.6eV makes it possible to assign the two main shake-up

structures, which both contain correlation satellites. As can be seen from table 1, the calculated energies fall into two groups, one coming from the Kr3/2 and the other from the Kr3pl/2 core hole. See Figure 2. In con- clusion intermediate coupling plays an im- portant role to describe the complex Kr3d shake-up spectrum whereas for the Kr3p spectrum the spin-orbit coupling dominates.

The fine structure in this latter spectrum most probably originates from correlation effects.

The final assignment of these spectra has to await more eliborate relativist& calculation including the electron correlation effects and should i l s o include calculations of the intensities of the states involved.

Acknowledgement

The authors want to thank J.O.Forsell and H.Ryd&er for their skillfull assistance. This work has been supported by the Swedish Natural Research Council.

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