mechanisms of photo double ionization of helium by 529 ev photons alexandra knapp group of r....
TRANSCRIPT
![Page 1: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/1.jpg)
Mechanisms of
Photo Double Ionization of Helium
by 529 eV Photons
Alexandra Knapp
Group of R. Dörner and H. Schmidt-BöckingUniversity of Frankfurt, Germany
![Page 2: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/2.jpg)
0
Ene
rgy
Single ionization
25 eV … 79 eV: only single ionization
0
Ene
rgy
Double ionization
79 eV and higher: single + double ionization
![Page 3: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/3.jpg)
Shake off
![Page 4: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/4.jpg)
Shake off
First electron absorbs photon and removes from the nucleus
![Page 5: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/5.jpg)
Shake off
![Page 6: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/6.jpg)
Shake off
Change of the effektiv nuclear charge
![Page 7: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/7.jpg)
Shake off
Second electron is in its eigenstate Only single ionization occurs
![Page 8: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/8.jpg)
Shake off
Second electron is NOT in its eigenstate Shake off
![Page 9: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/9.jpg)
Electron-electron scattering (TS1)
![Page 10: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/10.jpg)
Electron-electron scattering (TS1)
![Page 11: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/11.jpg)
Electron-electron scattering (TS1)
![Page 12: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/12.jpg)
Electron-electron scattering (TS1)
![Page 13: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/13.jpg)
Electron-electron scattering (TS1)
![Page 14: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/14.jpg)
Electron-electron scattering (TS1)
![Page 15: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/15.jpg)
Electron-electron scattering (TS1)
![Page 16: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/16.jpg)
Electron-electron scattering (TS1)
![Page 17: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/17.jpg)
Electron-electron scattering (TS1)
90°
(e,2e) like collision between the two electrons
![Page 18: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/18.jpg)
Photon energy above the threshold [eV]
TS1
Shake off
Shake off + TS1
Ratio of double to single ionization (theory)
%
![Page 19: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/19.jpg)
with electric field
COLTRIMS
![Page 20: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/20.jpg)
with electric + magnetic field
COLTRIMS
Collecting electrons up to 60 eV with 4 solid angle with a combination
of an electric and a magnetic field
![Page 21: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/21.jpg)
Questions
• Is the assumption of a two-step model
valid?
• Energy sharing
• Asymmetry parameter
• Mechanisms of photo double ionization
• Angular distributions
![Page 22: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/22.jpg)
Energy sharing
Extreme asymmetric energy sharing
CCC-Calculation A. Kheifets, I. Bray
![Page 23: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/23.jpg)
Asymmetry parameter
Fast electron absorbs photon energy and its angular momentum
Polynomial fit
![Page 24: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/24.jpg)
Asymmetry parameter
Two-step model is valid
Polynomial fit
![Page 25: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/25.jpg)
Shake off TS1
CCC-Calculation CCC-Calculation
Very slow electrons: 2 eV
Angular distributions
Faster electrons: 30 eV
The fast electron (indicated by the red arrow) is fixed into the direction of the polarization
![Page 26: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/26.jpg)
fast electron (420 eV)
fast electron (448 eV)
s
low
er e
lect
ron
(2 e
V)
s
low
er e
lect
ron
(30
eV)
TDCS for Eslow = 2 eV and 30 eV
![Page 27: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/27.jpg)
fast- slow =180
fast- slow =90
fast electron (420 eV)
fast electron (448 eV)
s
low
er e
lect
ron
(2 e
V)
s
low
er e
lect
ron
(30
eV)
Shake off and TS1 can be seen for all angles
![Page 28: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/28.jpg)
fast electron (420 eV)
fast electron (448 eV)
s
low
er e
lect
ron
(2 e
V)
s
low
er e
lect
ron
(30
eV)
Comparison between experiment and theory
![Page 29: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/29.jpg)
Conclusion
• TDCS of the DPI of Helium were measured at 450 eV above the threshold
• electrons are distinguishable because of the asymmetric energy sharing
=2 for very fast and =0 for very slow electrons
• very slow ( 2 eV) electrons: Shake off
• slightly faster ( 30 eV) electrons: TS1
![Page 30: Mechanisms of Photo Double Ionization of Helium by 529 eV Photons Alexandra Knapp Group of R. Dörner and H. Schmidt-Böcking University of Frankfurt, Germany](https://reader036.vdocuments.site/reader036/viewer/2022062714/56649d135503460f949e78ed/html5/thumbnails/30.jpg)
Reinhard Dörner Horst Schmidt-BöckingAlexandra KnappThorsten WeberSven SchößlerTill JahnkeJürgen Nickles Susanne KammerOttmar JagutzkiLothar Schmidt
C. Lewis CockeTimur Osipov
Michael H. PriorJürgen Rösch
Allen Landers
Anatoli Kheifets
Igor Bray
University Frankfurt:
Kansas State University:
LBNL:
Western Michigan University:
Australian National University Canberra:
Murdock University Perth:
Supported by BMBF, DFG and DOE