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Molecular Tunneling Ionization and Molecular Alignment

Investigating ionization and alignment of molecules in laser fields using theoretical and experimental methods. Comparing results with observations and developing a comprehensive theory.

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Molecular Tunneling Ionization and Molecular Alignment

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  1. Molecular Tunneling Ionization and Molecular Alignment X. M. Tong, Z. X. Zhao and C. D. Lin Physics Department, Kansas State University, Manhattan KS 66506 email: xmtong@phys.ksu.edu http://phys.ksu.edu/~xmtong

  2. Molecular Tunneling Ionization • Motivation: • Ionization; tunneling & multiphoton; • ADK (Ammosov, Delone and Krainov) model; • Experimental observations. • Theoretical Method: • Molecular orbital at asymptotical region; • Tunneling ionization; • How to compare with experiments? • Results and Discussion • D2/Ar, N2/Ar, O2/Xe, CO/Kr • S2/Xe, SO/Xe, NO/Xe • F2/Ar

  3. Atoms or Molecules in an Intense Laser Field Multiphoton Ionization: Tunneling Ionization Keldysh parameter

  4. Ionization of N2 and Ar Ip N2: 15.58 eV Ar: 15.76 eV 30 fs: Guo et al., PRA 58 (1998) R4271. 100 fs : DeWitt et al., PRL 87 (2001) 153001.

  5. Ionization of O2 and Xe Ip O2: 12.36 eV Xe: 12.13 eV Ionization supression Interference Model: Muth-Bohm et al., PRL 85 (2000) 2280. Failed for D2, F2 Effective Charge: Guo, PRL 85 (2000) 2276. 30 fs: Guo et al., PRA 58 (1998) R4271. 200 fs : Talebpour et al., JPB 29 (1996) L677.

  6. W.P. T.I. Atomic Tunneling Ionization

  7. Atomic Tunneling Ionization

  8. Atomic Tunneling Ionization

  9. W.P. T.I. F Molecular Tunneling Ionization

  10. A3 A2 Molecular Tunneling Ionization A1

  11. 3.5x1014 W/cm2 Ionization Rates of H2+ in a Static Field H2+ z F

  12. Ionization Rates of H2 H2 Saenz, PRA 61(2000) 051402. z F

  13. Ratio of Ionization Rates for N2:Ar and O2:Xe

  14. F Tunneling Ionization for Oriented Molecules

  15. X1013 W/cm2 q q Ionization for Oriented N2 Molecules

  16. X1013 W/cm2 q Ionization for Oriented O2 Molecules q F

  17. r z How to Compare with Experiments ?

  18. Ionization Rate, Probability and Signal D2/Ar

  19. D2 Energy Potential Molecular Vibration Effect

  20. N2/Ar Ip N2: 15.58 eV Ar: 15.76 eV 30 fs: Guo et al., PRA 58 (1998) R4271. 100 fs : DeWitt et al., PRL 87 (2001) 153001.

  21. O2/Xe Ip O2: 12.36 eV Xe: 12.13 eV 30 fs: Guo et al., PRA 58 (1998) R4271. 200 fs : Talebpour et al., JPB 29 (1996) L677.

  22. D2/Ar Ip D2: 15.47+0.8 eV Ar: 15.76 eV Expt: Wells et al., PRA 66 (2002) 013409.

  23. CO/Kr Ip CO: 14.01 eV Kr: 14.00 eV Expt: Wells et al., PRA 66 (2002) 013409.

  24. F2/Ar Ip F2: 15.70 eV Ar: 15.76 eV Expt: 100 fs : DeWitt et al., PRL 87 (2001) 153001.

  25. NO/Xe, S2/Xe and SO/Xe Ip NO: 9.26 eV S2: 9.36 eV SO: 10.29 eV Xe: 12.13 eV

  26. NO and Xe Expt: Wells et al., PRA 66 (2002) 013409. Xe Expt: Guo et al., PRA 58 (1998) R4271.

  27. S2 and Xe Expt: Wells et al., PRA 66 (2002) 013409. Xe Expt: Guo et al., PRA 58 (1998) R4271.

  28. SO and Xe Expt: Wells et al., PRA 66 (2002) 013409. Xe Expt: Guo et al., PRA 58 (1998) R4271.

  29. A3 A2 A1 Summary

  30. Summary • Develop a molecular tunneling ionization theory; • Study the diatomic molecular ionization; • Extend to triatomic molecules; • Different suppression mechanisms. The full paper can be downloaded from http://www.phys.ksu.edu/~xmtong/pub.html

  31. q F (2) Molecular Alignment (a) Angular dependent ionization signal; (b) How to Align a molecule.

  32. Molecular Alignment in laser field J. Ortigoso et al., JCP110,3870 Short pulse: revival; Long pulse: No

  33. Molecular Alignment Revival: Initial: Random Kick: Deposit J

  34. q F Molecular Alignment

  35. Molecular Alignment O2: Wjm = 1 (even J) or 0 (odd J) N2: Wjm = 1/3 (even J) or 2/3 (odd J)

  36. Kick or Push ? F Dt Pulse intensity 2x1013 W/cm2

  37. N2: (2x1013 : 8x1013)

  38. Revival O2: (2x1013 : 4x1013)

  39. Summary • Optimized revival can be achieved with a fixed laser intensity; • 10% to 20% enhancement for O2, and • 20% to 60% enhancement for N2; • maximum enhancement when the two field parallel.

  40. Summary

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