Abstract. In the framework of time-dependent density-functional theory, we study electron emission from Na clusters and the C 2 H 4 molecule as induced by irradiation with an intense pulse. The collision of a charged projectile on C 2 H 4 is also explored for comparison. We look in particular at the level depletion, i.e. the electron loss in each single-electron level separately. It is found that the distribution of electron loss depends sensitively on the photon frequency. Frequencies close to visible light remove electrons exclusively from the vicinity of the Fermi surface while light in the higher UV range (up to 20 eV for Na clusters and up to 136 eV for C 2 H 4 ) depletes all levels about equally strong, down to the deepest bound valence state.Confidential: not for distribution.

In the framework of time-dependent density functional theory (TDDFT), we study electronic emission from small Na clusters after irradiation by an intense femtosecond laser pulse. Photoelectron spectra (PES) are compared with level depletion, i.e., the electron loss at each single-electron level. Laser frequencies in the UV range (from 9 to 19 eV) are explored. We find a clear correlation of the peak areas in the photoelectron spectra with the state depletion. This thus allows experimental access to the ionization mechanism. This correlation, moreover, demonstrates that one can find a physical interpretation of the Kohn-Sham orbitals in PES, as in real-time TDDFT. 7