Auger electron and x-ray emission from high-z few-electron ions

Transcription

1 Auger electron and x-ray emission from high-z few-electron ions S. Fritzsche MPI für Kernphysik Heidelberg and GSI Darmstadt 4th August 2007 Main goal for studying high-z ions is the better understanding of: electron-photon interaction electron-electron interaction In the presence of strong or even (super-) critical fields relativistic and QED effects

2 FAIR: Facility for Antiproton and Ion Research electron-photon interaction Helmholtz Centre for Ion Research electron-electron interaction

3 Auger electron and x-ray emission from high-z few-electron ions S. Fritzsche MPI für Kernphysik Heidelberg and GSI Darmstadt 4th August 2007 Outline of this talk: i) Single-photon transitions: Electron capture ii) Multi-photon processes Sequential (photon-photon correlations,...) Non-sequential (two-photon transitions, entanglement,...) iii) Auger and electron loss processes into the continuum (coherence transfer, DR,...)

4 Auger electron and x-ray emission from high-z few-electron ions S. Fritzsche MPI für Kernphysik Heidelberg and GSI Darmstadt 4th August 2007 Outline of this talk: i) Single-photon transitions: Electron capture vs. excitation ii) Multi-photon processes Sequential (photon-photon correlations, entanglement,..) Non-sequential (two-photon transitions,...) iii) Auger and electron loss processes into the continuum Thanks to: Highly-charged ions (A. Surzhykov, T. Stöhlker & GSI group) Coherence transfer in inner-shell excited atoms (N. Kabachnik, A. Grum-Grzhimailo, K. Ueda & group)

5 Extreme Static Electromagnetic Fields Self Energy E 500 ev Z α 1 Uranium Vacuum Polarization Laser fields: 1022 W/cm2 Hydrogen E 10-6 ev Z α 10-2

6 Relativistic and quantum-electrodynamical corrections P 2 3s Uranium91+ relativistic nonrelativistic Relativistic contraction of the wave functions Use of the one-particle Dirac operator

7 Relativistic and quantum-electrodynamical corrections -- Test of QED in hydrogen-like uranium 2p3/2 2s1/2 P 2 3s Uranium91+ relativistic nonrelativistic M1 1s-Lamb Shift Use of the one-particle Dirac operator Lyα2 (E1) 1s1/2 Experiment: ev ± 4.6 ev Theory: Relativistic contraction of the wave functions Lyα1 (E1) 2p1/ ev A. Gumberidze, PhD thesis (2003), PRL 94 (2005)

8 Electron capture at storage rings into high-z ions ~ d M ies... polarization total cross sections d ~ M 2 d polarization angular distributions

9 Electron capture at storage rings into high-z ions ~ d M ies... polarization total cross sections d ~ M 2 d polarization Recent studies... angular distributions polarization ~ M No summation over polarization states! Alignment studies

10 So far... ~ total cross sections d M 2 polarization Electron capture at storage rings into high-z ions d ~ M 2 d polarization Recent studies... angular distributions ESR Alignment studies

11 So far... ~ total cross sections d M 2 polarization Electron capture at storage rings into high-z ions d ~ M 2 d polarization Recent studies... angular distributions ESR NESR GSI Alignment studies deceleratio n Injection Energy 400 MeV/u

12 Two-photon coincidence studies Coincidence measurement Normal (independent) measurement Photon-photon correlation functions: W RR, =? 1s1/2 Need for getting sensitive to the angle and/or polarization properties of the emitted particles!!

13 Two-photon coincidence studies Normal (independent) measurement Coincidence measurement Lengthy derivation in the framework of the density matrix theory. Photon-photon correlation functions: θrr = 0 deg U91+ θrr = 15 deg θrr = 90 deg observation angle θrr angular distribution 4 A Y 5 q 2q RR 2q differential alignment W RR, 1 θrr = 0 deg θrr = 15 deg θrr = 90 deg observation angle θ

14 γly angular distribution in dependence of θrr Coplanar geometry Differential alignment A 20 n RR 20 n RR U91+ A. Surzhykov, S.F. et al., JPB 35 (2002) 3713

15 Multiphoton processes with high-z ions Two-photon ionization of atomic inner-shells -- Two-photon ionization of atomic inner-shells 2 = Second-order amplitude: E1+E2+M1+... M = C 2 M 2 E ph ikr ikr e u p e f u p i E i E ph E Inner-shell processes: large photon energies (multi-photon mode) non-isolated resonances inherent coupling with valence electrons different time scales Fast decay Post-collision intercations Cross section Direct summation vs. Greens' functions nonresonant region Energy

16 P. Koval, S.F. and A. Surzhykov, JPB 37 (2004) 375 Two-photon ionization of hydrogen-like ions Two-photon ionization of atomic inner-shells -- effects of higher multipoles on angular distributions

17 P. Koval, S.F. and A. Surzhykov, JPB 37 (2004) 375 Two-photon ionization of hydrogen-like ions Two-photon ionization of atomic inner-shells -- effects of higher multipoles on angular distributions Fo rb idd MZ = ms + l + l = 5/2 en MZ = ms= 1/2 MZ = ms + l + l' = 1/2 MZ = ms= 1/2

18 A.Surzhykov et al. PRA 71 (2004) Two-photon decay of highly-charged ions 2s1/2 E1E1 1s1/2 tot E1E1=8.229 Z 6

19 A.Surzhykov et al. PRA 71 (2004) Two-photon decay of highly-charged ions 2s1/2 E1E1 + E1M2 + M1M1+E2E2 + E2M1... 1s1/2 Higher multipoles give rise to an asymetrical shift tot E1E1=8.229 Z 6 2 W ~1 cos

20 S. Fritzsche, JESRP (2001) 1155; Phys. Scr. T100 (2002) 46 RATIP Relativistic Atomic Transition and Ionization Properties (CPC library) Relativistic CI wave functions including QED estimates and mass polarization RELCI, CPC 148 (2002) 103 LSJ spectroscopic notation from jj-coupled computations LSJ, CPC 157 (2003) 239 nc P J M = c r r P J M r Auger rates, angular distributions and spin polarization; level widths AUGER Many-electron basis (wave function expansions) Construction and classification of N-particle Hilbert spaces Shell model: Systematically enlarged CSF basis Interactions Dirac-Coulomb Hamiltonian Photoionization cross sections and (non-dipole) angular parameters PHOTO Radiative and dielectronic recombination; angle-angle correlations Breit interactions + QED Electron continuum; scattering phases Coherence transfer and Rydberg dynamics...

21 Polarization entanglement in the two-photon decay of hydrogen-like ions 2s1/2, mj=±½ 2s1/2 M1 1s1/2 E1 σ+ σ E1 σ σ+ ω1 ω2 ω1 1s1/2, mj=±½ Z= dw =Z 6 10 x dx 2 (normalized) spectral distribution function Predicted by M. Göppert-Mayer (1931) First decay rate estimations by Breit and Teller (1940) First observed only in 1975 by O Connell et al. Polarization correlation (for back-to-back geometry) measured and found to violate Bell inequality (Perrie et al.,1985) 1,4 Z=1 1,2 1,0 0,8 0,6 0,4 0,2 0,0 0,0 0,2 0,4 0,6 energy sharing x 0,8 1,0

22 Polarization entanglement in the 2s1/2 1s1/2 two-photon decay -- unpolarized initial state The opening angle between the photons is the only free parameter in this case. s = 1/2 = =1 s = 1/2 2 Bell state (=maximally entangled!) Experiments so far: only for hydrogen and in trivial (back-to-back) geometry Perrie et al., PRL 54, 1790 (1985) Haji-Hassan et al., J. Phys. B 24, 5035 (1991)

23 Polarization entanglement in the 2s1/2 1s1/2 two-photon decay -- relativistic increase

24 Polarization entanglement in the 2s1/2 1s1/2 two-photon decay -- relativistic increase Need for getting sensitive to the angle and/or polarization properties of the emitted particles!!

25 Auger emission of excited atomic states A+(K-1) energy εauger excitation decay A++(L-2) L K H = i h i u r i A H = hi i i j 1 r ij

26 Auger emission of excited atomic states A+(K-1) energy εauger excitation decay A++(L-2) L A K H = i H = h i u r i hi i i j 1 r ij Wentzel's ansatz: Autoionization is caused by electron-electron interactions which cannot be considered in an one-particle picture. i j 1 r ij i u r i Ideal tool for a better understanding of electronic correlations!

27 Coherence transfer in the Auger cascades of noble gases -- a signature of the atomic double slit resonantly excited noble gas np --> (n+2)s, (n+2)d Well isolated resonances! ω12 >> Γ A2+ Decay branches are independent; path can be determined by measuring the energy spectrum. Collaboration with Nicolai Kabachnik (Bielefeld); experiments by Kyioshi Ueda and coworkers at SPring8, Japan

28 Coherence transfer in the Auger cascades of noble gases -- a signature of the atomic double slit resonantly excited noble gas np --> (n+2)s, (n+2)d Overlapping resonances! ω12 < Γ How depend the (Auger) electron emission and, in particular, their angular distribution on the splitting of the resonances? Young's experiment: (Feynman-Lectures 1962) P1 ~ φ 2 P12 = φ1 + φ2 2 double slit wall A2+

29 Coherence transfer in the Auger cascades of noble gases -- a signature of the double slit Angular distribution of the second-step electron for double-slit decay: J J ' c W = J 1, J 1 ' ; J 2 J 1, J 1 ' k, J J ' J J ' J 1 1, 1 1 dynamics of Auger emission electron-electron correlations coherent summation P k cos J 1' memory on the creation process geometry of the double slit Second-step electron perpendicular to the photon polarization θ = 270 A rg n o Coincidence between the resonance Ar(1P1) - Ar+(3s3p5 (1P)4s 2 P1/2,3/2) and the second-step electron Ar+ (3s 3p5 (1P) 4s 2P1/2,3/2) - Ar2+ (3p4 3P) und - Ar2+ (3p4 1D2) I(θ) = A0 + A2 cos 2θ + A4 cos 4θ Ueda et al., JPB 34 (2001) 107 Ueda et al., Phys. Rev. Lett. 95 (2003)

30 Excitation and two-step Auger cascades in noble gases Photoabsorption: Ar (2p6 3s2 3p6 1S0) + hν Ar*(2p5 3s2 3p6 4s 1P1) First decay: Ar*(1P1) Ar*+(3s 3p5 (1,3P) 4s 2P or 4P) + ea1 Second decay: Ar*+ (3s 3p5 (1P) 4s 2P1/2,3/2) Ne: 500 : 1 Ar: 80 : 1 Kr: 25 : 1 Xe: 8:1 Ar2+ (3p4 3P or 1D) + ea2 Aresonance Aintercombination Xenon: 4d-16p 1,3P 1 5s-26p; 5s5p56p Relativity enters here in two ways!

31 Excitation and two-step Auger cascades in noble gases Photoabsorption: Ar (2p6 3s2 3p6 1S0) + hν Ar*(2p5 3s2 3p6 4s 1P1) First decay: Ar*(1P1) Ar*+(3s 3p5 (1,3P) 4s 2P or 4P) + ea1 Second decay: Ar*+ (3s 3p5 (1P) 4s 2P1/2,3/2) Ne: 500 : 1 Ar: 80 : 1 Kr: 25 : 1 Xe: 8:1 Ar2+ (3p4 3P or 1D) + ea2 Aresonance Aintercombination excitation hν Xenon: 4d-16p 1,3P 1 5s-26p; 5s5p56p Kitajima et al., JPB 34 (2001) 3829; JPB 35 (2002) ω12 < Γ subsequent decay Radiative and Auger processes are not longer independent!

32 Auger emission of excited atomic states A+(K-1) energy εauger excitation decay A++(L-2) L A K H DCB = h D i i i j 1 r ij i j i r i j r j 1 [ i j ] 2 2r ij r ij Wentzel's ansatz: Autoionization is caused by electron-electron interactions which cannot be considered in an one-particle picture. i j 1 b i, j r ij i u r i Breit interaction

33 Auger emission of excited atomic states energy A+(K-1) εauger excitation A++(L-2) L K decay A Zero-degree Auger Projectile Spectroscopy (ZAPS) of relativistic electrons in beam direction with laboratory energies up to about 0.5 MeV and high spectrometer resolution of Δp/p 10-4 Advantages: single and preselected charge state of the projectiles considerably simplifies the identification of lines no line blending due to the mixture of different charge states studies along the isoelectronic sequences PRA31 (1985) 684

34 Differential cross sections in kinematically complete experiments -- Electron spectroscopy working group of SPARC S. Hagmann and coworkers (2007) The dynamics of (projectile) excitation and ionization processes is essential determined by the momentum transfer in the reaction (longitudinal vs. transverse)

35 Collaboration: C. Brandau (GSI), S. Schippers (Gießen) Dielectronic recombination in ion-electron collisions Low-energetic collisions nl Resonant (non-radiative) capture of an electron into a bound state 2p Time-reversed Auger process 2s Important charge exchange process for multi-electron ions Aq+(1s2 2s) + e A(q-1)+(1s2 2p nl) A(q-1)+(1s2 2s2) + hν doubly excited intermediate state dielectronic capture radiative stabilization

36 Collaboration: C. Brandau (GSI), S. Schippers (Gießen) Dielectronic recombination in ion-electron collisions Low-energetic collisions nl Resonant (non-radiative) capture of an electron into a bound state 2p Time-reversed Auger process 2s Important charge exchange process for multi-electron ions A(q-1)+(1s2 2p nl) A(q-1)+(1s2 2s2) + hν doubly excited intermediate state radiative stabilization -1 j=7/ n=30 n=31 n=32 n=33 n=34 n= n=29 n=27 j=9/2 n=24 n=21 5 n=22 n=23 j=5/2 n=26 n= Studies on Rydberg series Lamb-shift in heavy Li-like ions Measurement of nuclear properties Nuclear charge radii Nuclear moments Tests of nuclear-structure theory Shape and asymmetries of (Fano-) resonances 2 1s 2p1/2 nl j resonances j=3/2 3 Applications: 2 1s 2p 3/2 5l j resonances Rate coefficient (10 cm s ) dielectronic capture Recombination of Li-like U89+ n=25 Aq+(1s2 2s) + e 160 Electron-ion collision energy (ev) 180

37 Atomic and heavy-ion theory within the SPARC collaboration -- Recent developments and progress Key topics of this collaboration: Test of quantum electrodynamics in strong fields for light and high-z ions... two-times Green's functions; 2-photon, 3-photon (??) diagrams; differences with experiment especially for the HFS; systematic QED approach in the MBPT framework Collision dynamics in strong fields at relativistic and ultrarelativistic energies... U28+ electron loss; few-body dynamics; polarization effects; multi-electron processes Atomic physics techniques applied to nuclear physics Multi-photon processes... sequentiell vs. direct ionization Antiproton physics Test of fundamental interactions and symmetries beside of QED Interaction of ions with intensive (laser) light... high-harmonics generation up to kev/mev GSI

38 FAIR: Facility for Antiproton and Ion Research Theory Group Meeting Atomic Physics in Strong Fields July 2007, GSI Darmstadt electron-photon interaction electron-electron interaction In the presence of strong or even (super-) critical fields relativistic and QED effects dynamics of excitation and decay processes resonance enhancement collision dynamics with radioactive beams