Dissociation and ionization of diatomc molecules steered by structured noise |
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| Anatole Kenfack | |
| Freie Universität Berlin | |
| The central question that we try to solve here is how both the dissociation and ionization channels can be separated; in other words can one achieve dissociation without ionization or vice versa? Recent experiments show that the photo-ionization process has a strong influence on the subsequent dissociation[1,2]. This is in fact a longstanding problem which continues to attract the attention of the molecular physics community[3,4] despite some improvements by means of linearly/circularly polarized chirped laser pulses[5,6]. Given that achieving dissociation without ionization is non trivial, it is thus natural to think of a stochastic forcing as an alternative to the laser field. To begin with, I show how one can use a structure noise (the so-called white shot noise) to efficiently achieve dissociation of heteronuclear molecules such as HF, HCl, etc... Results of both quantum and classical approaches are compared, revealing a certain discrepancy[7]. Then in order to perceive both ionization and dissociation channels separately, I consider the nature's simplest molecule, the Hydrogen molecular ion H2+. In this model, the structured noise is applied along the molecular axis thereby leading to a cylindrical symmetry; and the coulomb singularity is conveniently removed by means of the Bessel Fourier Series. The dynamics is thus beyond the Born-Oppenheimer approximation, allowing one degree of freedom for the nuclei and two for the electron. I show that for appropriate noise parameters, one can achieve substantial dissociation without ionization [8]. [1] T. D. G. Walsh et al., Phys. Rev. A58, 3922 (1998) [2] K. Saendig, H. Figger, and T. W. Haensch, Phys. Rev. Lett. 85, 4876 (2000) [3] M. F. Kling et al., Science 312, 246 (2006). [4] H. Feng, C. Ruiz and A. Becker, Phys. Rev. Lett. 99, 083002 (2007). [5] J. H. Kim, W. K. Liu, and F. R. W. McCourt, J. Chem. Phys. 112, 1757 (2000). [6] S. Chelkowski, A. D. Bandrauk, P. B. Corkum, Phys. Rev. Lett.65, 2355 (1990). [7] A. Kenfack, and J. M. Rost, J. Chem. Phys.123, 204322 (2005). [8] A. Kenfack, J. M. Rost, and F. Grossmann, New J. of Phys. 10, 013020 (2008) |