Above-threshold ionization and laser-induced electron diffraction in diatomic molecules
| Autor: | Jens Biegert, Noslen Suarez, Marcello F. Ciappina, Maciej Lewenstein, Benjamin Wolter, Alexis Chacón |
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| Rok vydání: | 2016 |
| Předmět: |
Physics
Atomic Physics (physics.atom-ph) Above threshold ionization Center (category theory) FOS: Physical sciences Electron 01 natural sciences Diatomic molecule Physics - Atomic Physics 3. Good health 010305 fluids & plasmas Dipole Electron diffraction Ionization 0103 physical sciences Physics::Atomic Physics Atomic physics 010306 general physics Wave function |
| Zdroj: | Physical Review A |
| ISSN: | 2469-9934 2469-9926 |
| Popis: | Strong field photoemission and electron recollision provide a viable route to extract electronic and nuclear dynamics from molecular targets with attosecond temporal resolution. However, since an {\em ab-initio} treatment of even the simplest diatomic systems is beyond today's capabilities approximate qualitative descriptions are warranted. In this paper, we develop such a theoretical approach to model the photoelectrons resulting from intense laser-molecule interaction. We present a general theory for symmetric diatomic molecules in the single active electron approximation that, amongst other capabilities, allows adjusting both the internuclear separation and molecular potential in a direct and simple way. More importantly we derive an analytic approximate solution of the time dependent Schr\"odinger equation (TDSE), based on a generalized strong field approximation (SFA) version. Using that approach we obtain expressions for electrons emitted transition amplitudes from two different molecular centres, and accelerated then in the strong laser field. One innovative aspect of our theory is the fact that the dipole matrix elements are free from non-physical gauge and coordinate system dependent terms -- this is achieved by adapting the coordinate system, in which SFA is performed, to the centre from which the corresponding part of the time dependent wave function originates. Our analytic results agree very well with the numerical solution of the full three-dimensional TDSE for the H$_2^+$ molecule. Moreover, the theoretical model was applied to describe laser-induced electron diffraction (LIED) measurements of O$_2^+$ molecules, obtained at ICFO, and reproduces the main features of the experiment very well. Our approach can be extended in a natural way to more complex molecules and multi-electron systems. Comment: 44 pages, 6 Figures |
| Databáze: | OpenAIRE |
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