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Chengjun LI, Lanzhou, China

Chengjun LI, Lanzhou, China 2 nd year of Ph.D in ISMO ( Institut des Sciences Moléculaires d’Orsay ) Université Paris Sud in the group of Prof. A Lahmam-Bennani and E M Staicu Casagrande

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Chengjun LI, Lanzhou, China

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  1. Chengjun LI, Lanzhou, China • 2ndyear of Ph.D in ISMO (Institut des Sciences Moléculaires d’Orsay) Université Paris Sud • in the group of Prof. A Lahmam-Bennani and E M StaicuCasagrande • Subject: Dynamique de l’ionisation simple ou double d’atomes et molécules: expériences (e2e) et (e3e)

  2. Contents Dynamics of double ionization (DI) process • Why? • Basic process of DI • Survey of some experimental results • Conclusion • Perspective

  3. Why? • The study of multiple ionizationprocess by chargedparticle impact is of considerableinterest in many branches of physics and other science (astrophysics, plasma physics, life science etc.) • Electron impact single ionization(SI) or double ionization(DI) is one of simplest and mostfundamental of suchprocesses.

  4. (e2e) & (e3e) experiments • fundamental information on • the dynamics of single ionization (e2e)or double ionization (e3e) • the projectile-target interactions • the e–e correlations • momentum space electron wavefunction of the target: electron momentum spectroscopy (EMS)

  5. 2+ A Basic process of (e3e) experiment e- + A A++ + e- + e- + e- ejected ec scattered ea incident e0 ejected eb

  6. Analyseur-C Analyseur-A Analyseur-B Apparatus

  7. Experimental parameters for DI (e,3e) : 3 electrons detected (e,3-1e) :2 electrons detected 5 eV Undetected 658 eV 500 eV 74 eV

  8. Different DI mechanisms One interaction with target Two interactions with target 1st-order Two-Step1 Shake-Off 2nd-order Two-Step2

  9. (e,3-1e) results on DI of He First order mechanism : * BBK model (dotted blue curve)

  10. (e,3-1e) results on DI of He First order mechanism : * BBK model (dotted blue curve) Second order mechanisms: * TS2-MECG (Two Step 2-Monte Carlo Event Generator) (dashed green curves) * Second-Born model (full black curves)

  11. E M Staicu Casagrande, C Li , A Lahmam-Bennani et al. J. Phys. B: At. Mol. Opt. Phys. 44 (2011) 055201

  12. Conclusion (at this date) • Our data show that under the present kinematics the 2nd order DI mechanism dominatesover the 1st order (SO and TS1) and is responsible for the measured features and structures of the lobes. • Theoretical calculations taking into account 2nd order DI mechanism (TS2-MCEGand B2) correctly predict the positions of both the forward and the backward lobes.

  13. Perspective • The (e,3-1e) study of the DI mechanism is being extended to other targets: Ne, Ar, N2 etc • A full (e,3e) experiment on N2 has been recently performed and is still in the analysis stage , and new (e3e)experiments on N2with different kinematics is underway.

  14. Merci beaucoup pour votre attention!

  15. TS2 kinematical analysis • IP+=24.6 IP2+=79 E0=658 Ea=500 Eb=75Ec=5 E0 – Ea* = E0sin2(θa*)

  16. TS2 kinematical analysis

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