Imaging of molecular orbitals from high-order: Harmonic spectra: Challenges in theory |
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| Richard Taieb | |
| Université Pierre et Marie Curie, Paris | |
| A few years ago, it has been shown that one could reconstruct the spatial dependence of the 3sg Highest-Occupied Molecular orbital (HOMO) in N2 through the analysis of the harmonic spectra generated by molecules oriented in space [1]. The conceptual framework of the approach is based on the so-called "Strong-Field Approximation" treatment of the harmonic generation process that links the harmonic phases and amplitudes to the ones of the bound-free molecular dipole. Then the HOMO of the molecule can be deduced from a tomographic analysis of the harmonic signals originating from molecules with different alignments in space with respect to the polarization of the pump laser, see [2] and references therein. Further generalizations of these pioneering results are under active investigations from both the experiment and theory sides. For recent results obtained in CO2, see [3]. So far, the agreement between theory and experiment is not completely satisfactory. In our presentation, we shall address several issues directly related to the theoretical treatment of this class of processes and we shall discuss different strategies under development aiming at filling the gap between theory and experiment. [1] J. Itatani et al., NATURE 432, 867 (2004). [2] M. Lein, JPB 40, R135 (2007). [3] W. Bouttu et al., NATURE PHYSICS 4, 545 (2008). |