Molecular Tunneling Ionization and Molecular Alignment X M

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

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 • D 2/Ar, N 2/Ar, O 2/Xe, CO/Kr • S 2/Xe, SO/Xe, NO/Xe • F 2/Ar

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

Ionization of N 2 and Ar N 2: Ar: 30 fs: Guo et al. , PRA 58 (1998) R 4271. 100 fs : De. Witt et al. , PRL 87 (2001) 153001. Ip 15. 58 e. V 15. 76 e. V

Ionization of O 2 and Xe O 2: Xe: Ionization supression Ip 12. 36 e. V 12. 13 e. V Interference Model: Muth-Bohm et al. , PRL 85 (2000) 2280. Failed for D 2, F 2 Effective Charge: Guo, PRL 85 (2000) 2276. 30 fs: Guo et al. , PRA 58 (1998) R 4271. 200 fs : Talebpour et al. , JPB 29 (1996) L 677.

Atomic Tunneling Ionization W. P. T. I.

Atomic Tunneling Ionization

Atomic Tunneling Ionization

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

Molecular Tunneling Ionization A 1 A 2 A 3

+ in a Static Field Ionization Rates of 2 H 3. 5 x 1014 W/cm 2 H 2+ z F

Ionization Rates of 2 H H 2 Saenz, PRA 61(2000) 051402. z F

Ratio of Ionization Rates for 2: Ar N and O 2: Xe

Tunneling Ionization for Oriented Molecules F

Ionization for Oriented 2 NMolecules X 1013 W/cm 2 q q

Ionization for Oriented 2 OMolecules X 1013 W/cm 2 q F q

How to Compare with Experiments ? r z

Ionization Rate, Probability and Signal D 2/Ar

Molecular Vibration Effect D 2 Energy Potential

N 2/Ar N 2: Ar: 30 fs: Guo et al. , PRA 58 (1998) R 4271. 100 fs : De. Witt et al. , PRL 87 (2001) 153001. Ip 15. 58 e. V 15. 76 e. V

O 2/Xe O 2: Xe: 30 fs: Guo et al. , PRA 58 (1998) R 4271. 200 fs : Talebpour et al. , JPB 29 (1996) L 677. Ip 12. 36 e. V 12. 13 e. V

D 2/Ar Ip D 2: 15. 47+0. 8 e. V Ar: 15. 76 e. V Expt: Wells et al. , PRA 66 (2002) 013409.

CO/Kr CO: Kr: Expt: Wells et al. , PRA 66 (2002) 013409. Ip 14. 01 e. V 14. 00 e. V

F 2/Ar F 2: Ar: Expt: 100 fs : De. Witt et al. , PRL 87 (2001) 153001. Ip 15. 70 e. V 15. 76 e. V

NO/Xe, S 2/Xe and SO/Xe NO: S 2: SO: Xe: Ip 9. 26 e. V 9. 36 e. V 10. 29 e. V 12. 13 e. V

NO and Xe Expt: Wells et al. , PRA 66 (2002) 013409. Xe Expt: Guo et al. , PRA 58 (1998) R 4271.

S 2 and Xe Expt: Wells et al. , PRA 66 (2002) 013409. Xe Expt: Guo et al. , PRA 58 (1998) R 4271.

SO and Xe Expt: Wells et al. , PRA 66 (2002) 013409. Xe Expt: Guo et al. , PRA 58 (1998) R 4271.

Summary A 1 A 2 A 3

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

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

Molecular Alignment in laser field J. Ortigoso et al. , JCP 110, 3870 Short pulse: revival; Long pulse: No

Molecular Alignment Initial: Random Revival: Kick: Deposit J

Molecular Alignment q F

Molecular Alignment O 2: Wjm = 1 (even J) or 0 (odd J) N 2: Wjm = 1/3 (even J) or 2/3 (odd J)

Kick or Push ? F Dt Pulse intensity 2 x 1013 W/cm 2

N 2: (2 x 1013 : 8 x 1013)

Revival O 2: (2 x 1013 : 4 x 1013)

Summary (a) (b) (c) (d) Optimized revival can be achieved with a fixed laser intensity; 10% to 20% enhancement for O 2, and 20% to 60% enhancement for N 2; maximum enhancement when the two field parallel.

Summary