Nonlinear Ionization of Molecules by Intense Transform-Limited Gaussian Laser Pulses

Samira Barmaki^*, Salima Hennani, Marc-André Albert, Stéphane Laulan

Laboratoire de Physique Computationnelle et Photonique, Université de Moncton Campus de Shippagan, Shippagan, Canada.

DOI: 10.4236/opj.2014.411031                

Abstract

We present in this paper an investigation of the nonlinear process of above-threshold ionization. The process arises when an atomic or molecular system, exposed to an intense laser pulse, continues to absorb more photons than that needed for the ionization to occur. We trigger this nonlinear process in a simple molecular system by exposing it to an intense transform-limited Gaussian laser pulse of 267-nm wavelength which is the third harmonic of an 800-nm wavelength Tisapphire laser. We explore the characteristics of the process by analyzing the kinetic-energy spectra of the electrons ejected from the molecular system under different laser peak intensities.

Keywords

Nonlinear Ionization Process, Intense Femtosecond Laser Fields, Multiphoton Absorption in Molecular Continuum, Transform-Limited Gaussian Laser Pulse

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	Diels, J.C. and Rudolph, W. (1996) Ultrashort Laser Pulse Phenomenon: Fundamentals, Techniques and Applications on Femtosecond Time Scale. Academic Press, New York.
[2]	Agostini, P. and DiMauro, L.F. (2004) The Physics of Attosecond Light Pulses. Reports on Progress in Physics, 67, 813-855. http://dx.doi.org/10.1088/0034-4885/67/6/R01
[3]	Yamanouchi, K. and Chin, S.L. (2007) Progress in Ultrafast Intense Laser Science III. Springler-Verlag, Berlin.
[4]	Krausz, F. and Ivanov, M. (2009) Attosecond Physics. Review of Modern Physics, 81, 163. http://dx.doi.org/10.1103/RevModPhys.81.163
[5]	Barmaki, S., Guessaf, K. and Laulan, S. (2011) Imaging of Ultrafast Electron Motion in Molecules. Canadian Journal of Physics, 89, 703-707. http://dx.doi.org/10.1139/p11-039
[6]	Agostini, P., Fabre, F., Mainfray, G., Petite, G. and Rahman, N.K. (1979) Free-Free Transitions Following Six-Photon Ionization of Xenon Atoms. Physical Review Letters, 42, 1127. http://dx.doi.org/10.1103/PhysRevLett.42.1127
[7]	Freeman, R.R., Bucksbaum, P.H., Milchberg, H., Darack, S., Schumacher, D. and Geusic, M.E. (1987) Above-Threshold Ionization with Subpicosecond Laser Pulses. Physical Review Letters, 59, 1092-1095. http://dx.doi.org/10.1103/PhysRevLett.59.1092
[8]	Schafer, K.J., Yang, B.R., DiMauro, L.F. and Kulander, K.C. (1993) Abovethreshold Ionization beyond the High Harmonic Cutoff. Physical Review Letters, 70, 1599. http://dx.doi.org/10.1103/PhysRevLett.70.1599
[9]	Paulus, G.G., Nicklich, W., Zacher, F., Lambropoulos, P. and Walther, H. (1996) High-Order Above-Threshold Ionization of the Atomic Hydrogen Using Intense, Ultrashort Laser Pulses. Journal of Physics B: Atomic, Molecular and Optical Physics, 29, L249-L256.
[10]	Javanainen, J., Eberly, J.H. and Su, Q.C. (1988) Numerical Simulations of Multiphoton Ionization and Above-Threshold Electron Spectra. Physical Review A, 38, 3430. http://dx.doi.org/10.1103/PhysRevA.38.3430
[11]	Cormier, E., Garzella, D., Breger, P., Agostini, P., Chériaux, G. and Leblanc, C. (2001) Above-Threshold Ionization Contrast and Channel Closure in Argon. Journal of Physics B: Atomic, Molecular and Optical Physics, 34, L9-L17.
[12]	Becker, W., Grasbon, F., Kopold, R., Milosevic, D.B., Paulus, G.G. and Walther, H. (2002) Above-Threshold Ionization: From Classical Features to Quantum Effects. Advances in Atomic Molecular and Optical Physics, 48, 35-98. http://dx.doi.org/10.1016/S1049-250X(02)80006-4
[13]	Xiang, Y., Niu, Y. and Gong, S. (2009) Above-Threshold Ionization by Few-Cycle Nonlinear Chirped Pulses. Physical Review A, 80, Article ID: 023423. http://dx.doi.org/10.1103/PhysRevA.80.023423
[14]	Nakajima, T. (2007) Above-Threshold Ionization by Chirped Laser Pulses. Physical Review A, 75, Article ID: 053409. http://dx.doi.org/10.1103/PhysRevA.75.053409
[15]	Laulan, S., Ba, H.S. and Barmaki, S. (2014) Excitation and Ionization of the Hydrogen Atom by Intense Femtosecond Chirped Laser Pulses. Canadian Journal of Physics, 92, 194-199. http://dx.doi.org/10.1139/cjp-2013-0389
[16]	Laulan, S., Haché, J., Ba, H.S. and Barmaki, S. (2013) Ionization Process of Atoms by Intense Femtosecond Chirped Laser Pulses. Journal of Modern Physics, 4, 20-26. http://dx.doi.org/10.4236/jmp.2013.410A1002
[17]	Barmaki, S., Ba, H.S. and Laulan, S. (2013) Control of the Atomic Ionization with Short and Intense Chirped Laser Pulses. Journal of Modern Physics, 4, 27-31. http://dx.doi.org/10.4236/jmp.2013.410A1003
[18]	de Boor, C. (1978) A Practical Guide to Splines. Springer-Verlag, New York.
[19]	Bachau, H., Cormier, E., Decleva, P., Hansen, J.E. and Martin, F. (2001) Applications of B-Splines in Atomic and Molecular Physics. Reports on Progress in Physics, 64, 1815-1943. http://dx.doi.org/10.1088/0034-4885/64/12/205
[20]	Barmaki, S., Laulan, S., Bachau, H. and Ghalim, M. (2003) The Ionization of One-Electron Diatomic Molecules in Strong and Short Laser Fields. Journal of Physics B: Atomic, Molecular and Optical Physics, 36, 817-824. http://dx.doi.org/10.1088/0953-4075/36/5/303
[21]	Lee, T.G., Pindzola, M.S. and Robicheaux, F. (2009) Energy and Angular Differential Probabilities for Photoionization of He Using Chirped Attosecond Soft X-Ray Pulses. Physical Review A, 79, Article ID: 053420. http://dx.doi.org/10.1103/PhysRevA.79.053420
[22]	Saleh, B.E.A. and Teich, M.C. (2007) Fundamentals of Photonics. John Wiley and Sons Inc., Hoboken.