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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 20, Iss. 11 — May. 21, 2012
  • pp: 11700–11709
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Classical simulations of electron emissions from H 2 + by circularly polarized laser pulses

Cheng Huang, Zhihua Li, Yueming Zhou, Qingbin Tang, Qing Liao, and Peixiang Lu  »View Author Affiliations


Optics Express, Vol. 20, Issue 11, pp. 11700-11709 (2012)
http://dx.doi.org/10.1364/OE.20.011700


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Abstract

With the classical fermion molecular dynamics model (FMD), we investigated electron emissions from H 2 + by circularly polarized laser pulses. The obtained electron momentum distribution clearly shows an angular shift relative to the expected direction for H 2 + aligned parallel to the polarization plane, which is in good agreement with the recent experimental result. By tracing the classical trajectory, we provide direct evidence for the electron delayed emission with respect to the instant when the electric field is parallel to the molecular axis, which was regarded as the origin of the angular shift in the electron momentum distribution. Furthermore, we find that the angular shift decreases with increasing the laser wavelength.

© 2012 OSA

1. Introduction

Photoionization of atoms and molecules by the strong laser field [1

1. P. Agostini, F. Fabre, G. Mainfray, and G. Petite, “Free-free transitions following six-photon ionization of xenon atoms,” Phys. Rev. Lett. 42, 1127–1130 (1979). [CrossRef]

], as the doorway step of many strong field processes [2

2. E. Goulielmakis, M. Schultze, M. Hofstetter, V. S. Yakovlev, J. Gagnon, M. Uiberacker, A. L. Aquila, E. M. Gullikson, D. T. Attwood, R. Kienberger, F. Krausz, and U. Kleineberg, “Single-cycle nonlinear optics,” Science 320, 1614–1617 (2008). [CrossRef] [PubMed]

9

9. Q. Liao, Y. Zhou, C. Huang, and P. Lu, “Multiphoton rabi oscillations of correlated electrons in strong-field nonsequential double ionization,” New J. Phys. 14, 013001 (2012). [CrossRef]

], continued attracting much attention over the past thirty years. The simple-man model [10

10. P. B. Corkum, N. H. Burnett, and F. Brunel, “Above-threshold ionization in the long-wavelength limit,” Phys. Rev. Lett. 62, 1259–1262 (1989). [CrossRef] [PubMed]

, 11

11. K. J. Schafer, B. Yang, L. F. DiMauro, and K. C. Kulanderc, “Above threshold ionization beyond the high harmonic cutoff,” Phys. Rev. Lett. 70, 1599–1602 (1993). [CrossRef] [PubMed]

], that the electron firstly leaves the parent ion with zero longitudinal momentum by tunneling at maximum of the electric field and then is determined by the laser field, has obtained great success in understanding the dynamics of the strong field ionization [12

12. G. G. Paulus, W. Becker, W. Nicklich, and H. Walther, “Rescattering effects in above-threshold ionization: a classical model,” J. Phys. B 27, L703–L708 (1994). [CrossRef]

, 13

13. M. Lein, J. P. Marangos, and P. L. Knight, “Electron diffraction in above-threshold ionization of molecules,” Phys. Rev. A 66, 051404(R) (2002). [CrossRef]

]. Because of the increasingly deep study in the strong field ionization, more and more novel phenomena [14

14. C. I. Blaga, F. Catoire, P. Colosimo, G. G. Paulus, H. G. Muller, P. Agostini, and L. F. DiMauro, “Strong-field photoionization revisited,” Nat. Phys. 5, 335–338 (2009). [CrossRef]

18

18. M. Odenweller, N. Takemoto, A. Vredenborg, K. Cole, K. Pahl, J. Titze, L. Ph. H. Schmidt, T. Jahnke, R. Dörner, and A. Becker, “Strong field electron emission from fixed in space H2+ ions,” Phys. Rev. Lett. 107, 143004 (2011). [CrossRef] [PubMed]

] beyond the scope of the simple-man model are found. The peculiar low-energy structure [14

14. C. I. Blaga, F. Catoire, P. Colosimo, G. G. Paulus, H. G. Muller, P. Agostini, and L. F. DiMauro, “Strong-field photoionization revisited,” Nat. Phys. 5, 335–338 (2009). [CrossRef]

, 15

15. W. Quan, Z. Lin, M. Wu, H. Kang, H. Liu, X. Liu, J. Chen, J. Liu, X. He, S. Chen, H. Xiong, L. Guo, H. Xu, Y. Fu, Y. Cheng, and Z. Xu, “Classical aspects in above-threshold ionization with a mid-infrared strong laser field,” Phys. Rev. Lett. 103, 093001 (2009). [CrossRef] [PubMed]

] of ATI electron spectra is generally investigated and the role of the Coulomb potential of the parent ion has been identified [19

19. C. Liu and K. Z. Hatsagortsyan, “Origin of unexpected low energy structure in photoelectron spectra induced by midinfrared strong laser fields,” Phys. Rev. Lett. 105, 113003 (2010). [CrossRef] [PubMed]

,20

20. D. A. Telnov and S. I. Chu, “Low-energy structure of above-threshold-ionization electron spectra: role of the coulomb threshold effect,” Phys. Rev. A 83, 063406 (2011). [CrossRef]

]. The counterintuitive angular shift in the photoelectron momentum distribution for atoms in strong few-cycle circularly polarized laser pulses is also attributed to an intimate interplay between the external field and the binding potential [16

16. C. P. J. Martiny, M. Abu-samha, and L. B. Madsen, “Counterintuitive angular shifts in the photoelectron momentum distribution for atoms in strong few-cycle circularly polarized laser pulses,” J. Phys. B 42, 161001 (2009). [CrossRef]

].

2. The fermion molecular dynamics model

The classical fermion molecular dynamics model (FMD) was originally introduced by Kirschbaum and Wilets etal. [30

30. L. Wilets, E. M. Henley, M. Kraft, and A. D. MacKellar, “Classical many-body model for heavy-ion collisions incorporating the pauli principle,” Nucl. Phys. A 282, 341–350 (1977). [CrossRef]

, 31

31. C. L. Kirschbaum and L. Wilets, “Classical many-body model for atomic collisions incorporating the Heisenberg and Pauli principles,” Phys. Rev. A 21, 834–841 (1980). [CrossRef]

]. In order to prevent autoionization and collapse of the molecule, they add two momentum-dependent pseudopotentials to the usual Hamiltonian. The two pseudopotentials (VH, VP) constrain the motion to satisfy the Heisenberg uncertainty and the Pauli exclusion principles. Then Cohen introduces two additional terms Vm1, Vm2 to improve the treatment of the H2+ and H2 molecules [32

32. J. S. Cohen, “Molecular effects on antiproton capture by H2 and the states of pp¯ formed,” Phys. Rev. A 56, 3583–3596 (1997). [CrossRef]

]. Vm1 is a one-electron operator, and Vm2 is a two-electron operator. This extension avoids the overbinding of H2+ and H2 and successfully reproduces the Born-Oppenheimer ground state energies of H2+ and H2. Very recently, the FMD model was further developed to study successfully the dynamics of laser-driven D3+ by Lötstedt etal. [33

33. E. Lötstedt, T. Kato, and K. Yamanouchi, “Classical dynamics of laser-driven D3+,” Phys. Rev. Lett. 106, 203001 (2011). [CrossRef] [PubMed]

].

In the FMD model, the classical mechanical Hamiltonian of the H2+ ion is written
H=H0+VH+Vm1
(1)
where
H0=T+VCoul
(2)
is the usual Hamiltonian containing the kinetic energy and Coulomb potentials. VH is effective potential representing the quantum-mechanical effects of the Heisenberg uncertainty. Vm1 is the one-electron operator. The subscripts b and c represent protons. The subscripts 1 and o denote the electron and the midpoint of the molecule. The labels i and j represent any pair of these. The relative distance
rij=rjri,
(3)
the relative momentum
pij=mipjmjpimi+mj,
(4)
and the reduced mass
μij=mimjmi+mj,
(5)
The Hamiltonian for the H2+ ion is (atomic units are used throughout unless stated otherwise)
H=12mppb2+12mppc2+12mep121rb11rc1+1rbc+1μb1rb12f(rb1pb1;ξH)+1μc1rc12f(rc1pc1;ξH)+1μo1rbc2f(ro1po1;ξm1).
(6)
where
f(rp;ξ)=ξ24αexp{α[1(rpξ)4]}.
(7)

The proton mass mp=1836, and the electron mass me=1. The precise value of the constant α is unimportant. Here α is chosen to be 4.0. The parameters ξH =0.9428, ξm1=0.90 are selected to fit the ground-state energies of H and H2+.

The evolution of the molecular system is determined by the Hamilton’s classical equations of motion:
dridt=Hpi,
(8)
dpidt=Hri+qE(t).
(9)
where q is the electric charge of the particle and E(t) is the electric field of a circularly polarized laser pulse. At first the two protons are fixed at z=±1.1614 a.u. which is the equilibrium configuration of H2+ in this model, the position and the momentum of the electron are given randomly. Then the energy of the molecular system is minimized by solving the classical equations of motion with a dissipative term [30

30. L. Wilets, E. M. Henley, M. Kraft, and A. D. MacKellar, “Classical many-body model for heavy-ion collisions incorporating the pauli principle,” Nucl. Phys. A 282, 341–350 (1977). [CrossRef]

]. In this way we get some classical H2+ ions with the ground state energy −0.603 a.u. as pilot molecules. Secondly, we imparted a vibrational energy of 2.5 eV to the two protons of these pilot molecules. These pilot molecules are then allowed to evolve freely without the laser field. The positions and momenta of the electrons and protons of these pilot molecules at time nΔt provide the nth initial condition in the initial ensemble. In this way, a initial classical ensemble with enough classical trajectories is generated. Once the initial ensemble is obtained, the laser field is turned on and all trajectories are evolved in the combined Coulomb and laser fields. In our calculation a circularly polarized 800 nm, 6×1014 W/cm2 laser pulse with a 11-cycle sin2-shaped envelope is used. The electric field E(t) rotates in x-y plane.

3. Results and discussions

Figure 1(a) displays the two-dimensional photoelectron momentum distribution from H2+ aligned perpendicular to the polarization plane of circularly polarized laser pulses. The donut-shaped final electron momentum distribution shown in Fig. 1(a) agrees with the simple man model [10

10. P. B. Corkum, N. H. Burnett, and F. Brunel, “Above-threshold ionization in the long-wavelength limit,” Phys. Rev. Lett. 62, 1259–1262 (1989). [CrossRef] [PubMed]

]. Figure 1(c) shows the radial momentum distribution of the photoelectron in the polarization plane, and its maximum is located at 1.62 a.u. which is exactly equal to the peak amplitude A0 of the vector potential. The two-dimensional momentum distribution in z-y plane [Fig. 1(b)] is also consistent with the recent observation [Fig. 1(b) in [34

34. L. Arissian, C. Smeenk, F. Turner, C. Trallero, A. V. Sokolov, D. M. Villeneuve, A. Staudte, and P. B. Corkum, “Direct test of laser tunneling with electron momentum imaging,” Phys. Rev. Lett. 105, 133002 (2010). [CrossRef]

]] for atoms.

Fig. 1 Photoelectron momentum distributions from H2+ aligned along z axis for a clockwise circularly polarized 800 nm laser pulse at a peak intensity of 6×1014 W/cm2. (a) and (b) show the two-dimensional photoelectron momentum distributions in x-y and z-y planes, respectively. (c) is the photoelectron radial momentum distribution. The electric field E(t) rotates in x-y plane.

When H2+ is aligned perpendicular to the polarization plane, the electron momentum distribution in the polarization plane is an uniform donut. However, for the case of H2+ aligned parallel to the polarization plane, the ionization rate is expected to be largest when E(t) is aligned along the axis of the molecule [35

35. X. M. Tong, Z. X. Zhao, and C. D. Lin, “Theory of molecular tunneling ionization,” Phys. Rev. A 66, 033402 (2002). [CrossRef]

, 36

36. G. L. Kamta and A. D. Bandrauk, “Imaging electron molecular orbitals via ionization by intense femtosecond pulses,” Phys. Rev. A 74, 033415 (2006). [CrossRef]

]. Therefore, two maximum parts are expected to appear in the direction perpendicular to the molecular axis in the final electron momentum distribution. This prediction deviates from the recent experimental observation where two maximum parts are found in the first and third quadrants. Here we obtain the two-dimensional photoelectron momentum distribution in polarization plane for H2+ aligned along x axis by the classical FMD model, as shown in Fig. 2(a). It is obvious that there are two maximum parts in the first and third quadrants not in the expected y direction. This deviation from the expected direction is in qualitative agreement with recent experimental result [see Fig. 1(e) in [18

18. M. Odenweller, N. Takemoto, A. Vredenborg, K. Cole, K. Pahl, J. Titze, L. Ph. H. Schmidt, T. Jahnke, R. Dörner, and A. Becker, “Strong field electron emission from fixed in space H2+ ions,” Phys. Rev. Lett. 107, 143004 (2011). [CrossRef] [PubMed]

]]. The momentum in the direction perpendicular to the polarization plane is almost zero [Fig. 2(b)]. Figure 2(c) shows the radial momentum distribution with a maximum of 1.5 a.u., which is slightly smaller than the peak amplitude A0 of the vector potential. This is also qualitatively consistent with the experimental observation.

Fig. 2 Photoelectron momentum distributions from H2+ aligned along x axis for a clockwise circularly polarized 800 nm laser pulse at a peak intensity of 6×1014 W/cm2. (a) and (b) show the two-dimensional photoelectron momentum distributions in x-y and z-y planes, respectively. (c) is the photoelectron radial momentum distribution. The electric field E(t) rotates in x-y plane.

Fig. 3 A sample trajectory from Fig. 2. Panels (a), (b) and (c) show the electron energy, the electron coordinate x and y, and the electron momentum px and py versus time in unit of laser cycle, respectively. Panel (d) displays the electron trajectory in x-y plane. The arrows mark the ionization time. The black dash-dot curve is the sketch of the electric field along the molecular axis.

Figure 4 shows the ionization yield as a function of the ionization time in unit of laser cycle for H2+ aligned along z axis [Fig. 4(a)] and aligned along x axis [Fig. 4(b)]. The blue dashed curves mark those instants that the electric field is parallel to the molecular axis. For the perpendicular alignment, the ionization yield firstly increases and then decreases with the time, which is similar to the laser envelope. Compared with Fig. 4(a), it is clear that the ionization yield curve in Fig. 4(b) shows a series of peaks separated by a half-cycle of the laser field. Moreover, these ionization peaks are not located at those instants that the electric field is parallel to the molecular axis, but hundreds of attoseconds later. This provides the direct evidence for the delayed emission of the electron. Without the effect of the Coulomb potential on the free electron considered, the electron final momentum is obtained as pf =piA(ti). A(ti) is the vector potential at the instant of ionization ti, and pi is the initial electron momentum. Because the pi is small relative to A(ti), the final direction is significantly determined by the vector potential A(ti) at the instant of ionization. If the electron is emitted at the instant when the electric field is parallel to the molecular axis, the electron will appear in the direction (y axis) perpendicular to the molecular axis. Because of the time lag of hundreds of attoseconds relative to those instants when the electric field is parallel to the molecular axis, the electron gains a momentum with a tilt angle relative to the direction perpendicular to the molecular axis from the subsequent electric field. Thus the photoelectron momentum distribution shows an angular shift relative to the expected direction for the case of the parallel alignment.

Fig. 4 Panels (a) and (b) show the ionization yield versus the ionization time in unit of laser cycle for the cases of Figs. 1 and 2, respectively. The vertical blue dashed curves mark those instants when the electric field is parallel to the molecular axis. The green dash-dot curve is the sketch of the electric field along the molecular axis.

Our classical calculations have well reproduced the unexpected angular shift in the electron momentum distribution from H2+ aligned parallel to the polarization plane. The attosecond time lag of electron emissions, which is responsible for the angular shift, is confirmed by the back analysis of classical trajectories. This implies that classical simulations can well describe the electron emission of H2+ by circularly polarized laser pulses. By solving the two-dimensional TDSE of H2+, the angular shift feature of the experimental data are reproduced as a part [peaks II of Fig. 1(f)] of the numerical simulation in [18

18. M. Odenweller, N. Takemoto, A. Vredenborg, K. Cole, K. Pahl, J. Titze, L. Ph. H. Schmidt, T. Jahnke, R. Dörner, and A. Becker, “Strong field electron emission from fixed in space H2+ ions,” Phys. Rev. Lett. 107, 143004 (2011). [CrossRef] [PubMed]

]. However, the additional two prominent parts I and III near the axes [Fig. 1(f)], which do not exist in the experimental result, also appear in the numerical simulation. In our classical simulations the two additional parts are not found. In order to analyze the origin of the delayed electron emission with our model, we carefully examine the evolution of the classical ensemble in the circularly polarized laser pulses. We find the numbers of the electrons near the two protons are almost same at the instant when the electric field is parallel to the molecular axis. However, just after the electric field is parallel to the molecular axis many electrons are transferred to one of the protons and thus the electrons near one proton are much more than those near the other proton. This scenario is very similar to that reported by Takemoto et al. for linear polarization [17

17. N. Takemoto and A. Becker, “Multiple ionization bursts in laser-driven hydrogen molecular ion,” Phys. Rev. Lett. 105, 203004 (2010). [CrossRef]

]. We consider that the transient electron localization at one of the protons results in the dominant electron emissions just after the instant when the electric field is parallel to the molecular axis.

In addition, our calculations obtain a final radial momentum of 1.5 a.u., which is slightly smaller than the vector potential (1.62 a.u.). In [18

18. M. Odenweller, N. Takemoto, A. Vredenborg, K. Cole, K. Pahl, J. Titze, L. Ph. H. Schmidt, T. Jahnke, R. Dörner, and A. Becker, “Strong field electron emission from fixed in space H2+ ions,” Phys. Rev. Lett. 107, 143004 (2011). [CrossRef] [PubMed]

] the low final momentum is attributed to the non-zero initial momentum of the electron at the instant of ionization. Here by tracing the classical trajectory it is obtained that the electron is emitted with an initial momentum of 0.5 a.u., and there is a 106 degree angle between the initial momentum pi and the inverse of the vector potential at the instant of ionization −A(ti). If the Coulomb attraction between the parent ion and the escaping electron is neglected, the electron final momentum is 1.56 a.u., which is a little smaller than the vector potential but bigger than the final momentum obtained by our numerical calculations. This indicates that the non-zero initial momentum is one reason for the low final momentum but not the only reason. We suggest that Coulomb attraction between the parent ion and the escaping electron could also result in the decrease of the electron momentum.

We further explore the effect of the laser wavelength on the angular shift of aligned H2+ by circularly polarized laser pulses. Figures 5(a) and 5(c) show the two-dimensional photoelectron momentum distributions from H2+ aligned along x axis for circularly polarized laser pulses at I=6×1014 W/cm2, λ=1200 nm and 1600 nm, respectively. The electron momentum distributions for 1200 nm and 1600 nm both show clear angular shifts. Furthermore, by comparing Figs. 2(a), 5(a) and 5(c), it is obvious that the tilt angle decreases with the laser wavelength increasing. By analyzing the ionization yield curves for different laser wavelengths [Figs. 4(b), 5(b) and 5(d)], one can easily find that the longer the laser wavelength is, the smaller the time lag in the electron emission is. This wavelength dependence of the time lag is responsible for the decrease of the angular shift with the laser wavelength increasing. Since the final emission direction of the electron depends on the laser phase of ionization, the ionization time lag is presented in unit of laser cycle in this paper. In our calculations we find that the time lags in atomic units for different wavelengths are almost same. For the same time lag in atomic units the long wavelength corresponds to a smaller value of time lag in unit of laser cycle in comparison with the short wavelength. Thus the time lag in unit of laser cycle decreases with the laser wavelength increasing. In order to more clearly display the strong wavelength dependence of the angular shift, we present the tilt angle as a function of the laser wavelength in Fig. 6.

Fig. 5 The two-dimensional photoelectron momentum distributions from H2+ aligned along x axis for a clockwise circularly polarized laser pulse at I=6×1014 W/cm2, λ=1200 nm (a) and 1600 nm (c). (b) and (d) show the ionization yield versus the ionization time in unit of laser cycle for the cases of (a) and (c) respectively. The vertical red dashed curves mark those instants when the electric field is parallel to the molecular axis. The electric field E(t) rotates in x-y plane.
Fig. 6 Dependence of the tilt angle on the laser wavelength.

4. Conclusion

In conclusion, we have investigated the electron momentum distributions from H2+ by circularly polarized laser pulses with the classical fermion molecular dynamics model. For H2+ aligned perpendicular to the polarization plane, the electron momentum distribution exhibits donut-shaped structure which is similar to the case of atoms. For H2+ aligned parallel to the polarization plane the ionization events are clustered in the first and third quadrants in the electron momentum distribution, i.e., the ejection direction of the electron has a tilt angle relative to the y axis direction (the expected direction), which is in good agreement with the recent experimental result. By back analysis of classical trajectories we definitely confirm that this angular shift in the electron momentum distribution originates from the delayed emission of the electron [18

18. M. Odenweller, N. Takemoto, A. Vredenborg, K. Cole, K. Pahl, J. Titze, L. Ph. H. Schmidt, T. Jahnke, R. Dörner, and A. Becker, “Strong field electron emission from fixed in space H2+ ions,” Phys. Rev. Lett. 107, 143004 (2011). [CrossRef] [PubMed]

], i.e., most of electrons are emitted not at the instant when the electric field is parallel to the molecular axis, but hundreds of attoseconds later. Further study indicates that the angular shift from H2+ by circularly polarized laser pulses decreases with increasing the laser wavelength.

Acknowledgment

This work was supported by the National Natural Science Foundation of China under Grant No. 11004070, 10904045, National Science Fund for Distinguished Young Scholars under Grant No. 60925021, and the 973 Program of China under Grant No. 2011CB808103.

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Y. Zhou, Q. Liao, and P. Lu, “Mechanism for high-energy electrons in nonsequential double ionization below the recollision-excitation threshold,” Phys. Rev. A 80, 023412 (2009). [CrossRef]

30.

L. Wilets, E. M. Henley, M. Kraft, and A. D. MacKellar, “Classical many-body model for heavy-ion collisions incorporating the pauli principle,” Nucl. Phys. A 282, 341–350 (1977). [CrossRef]

31.

C. L. Kirschbaum and L. Wilets, “Classical many-body model for atomic collisions incorporating the Heisenberg and Pauli principles,” Phys. Rev. A 21, 834–841 (1980). [CrossRef]

32.

J. S. Cohen, “Molecular effects on antiproton capture by H2 and the states of pp¯ formed,” Phys. Rev. A 56, 3583–3596 (1997). [CrossRef]

33.

E. Lötstedt, T. Kato, and K. Yamanouchi, “Classical dynamics of laser-driven D3+,” Phys. Rev. Lett. 106, 203001 (2011). [CrossRef] [PubMed]

34.

L. Arissian, C. Smeenk, F. Turner, C. Trallero, A. V. Sokolov, D. M. Villeneuve, A. Staudte, and P. B. Corkum, “Direct test of laser tunneling with electron momentum imaging,” Phys. Rev. Lett. 105, 133002 (2010). [CrossRef]

35.

X. M. Tong, Z. X. Zhao, and C. D. Lin, “Theory of molecular tunneling ionization,” Phys. Rev. A 66, 033402 (2002). [CrossRef]

36.

G. L. Kamta and A. D. Bandrauk, “Imaging electron molecular orbitals via ionization by intense femtosecond pulses,” Phys. Rev. A 74, 033415 (2006). [CrossRef]

37.

Y. Zhou, Q. Liao, and P. Lu, “Complex sub-laser-cycle electron dynamics in strong-field nonsequential triple ionizaion,” Opt. Express 18, 16025–16034 (2010). [CrossRef] [PubMed]

38.

D. A. Wasson and S. E. Koonin, “Molecular-dynamics simulations of atomic ionization by strong laser fields,” Phys. Rev. A 39, 5676–5685 (1989). [CrossRef] [PubMed]

39.

Y. Zhou, C. Huang, A. Tong, Q. Liao, and P. Lu, “Correlated electron dynamics in nonsequential double ioniza-tion by orthogonal two-color laser pulses,” Opt. Express 19, 2301–2308 (2011). [CrossRef] [PubMed]

40.

T. Zuo and A. D. Bandrauk, “Charge-resonance-enhanced ionization of diatomic molecular ions by intense lasers,” Phys. Rev. A 52, R2511–R2514 (1995). [CrossRef] [PubMed]

41.

T. Seideman, M. Yu. Ivanov, and P. B. Corkum, “Role of electron localization in intense-field molecular ionization,” Phys. Rev. Lett. 75, 2819–2822 (1995). [CrossRef] [PubMed]

OCIS Codes
(020.4180) Atomic and molecular physics : Multiphoton processes
(260.3230) Physical optics : Ionization
(270.6620) Quantum optics : Strong-field processes

ToC Category:
Atomic and Molecular Physics

History
Original Manuscript: April 12, 2012
Revised Manuscript: May 4, 2012
Manuscript Accepted: May 4, 2012
Published: May 8, 2012

Citation
Cheng Huang, Zhihua Li, Yueming Zhou, Qingbin Tang, Qing Liao, and Peixiang Lu, "Classical simulations of electron emissions from H2+ by circularly polarized laser pulses," Opt. Express 20, 11700-11709 (2012)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-11-11700


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