We investigate high-order harmonic generation in a sequence of icosahedral fullerenes using the extension of the so-called three-step or Lewenstein model to the molecular case. The high harmonic spectra obtained at midinfrared wavelengths show modulations in the plateau region. These modulations are due to the coherent superposition of the contributions from the atomic centers in the molecule to the dipole moment. Results of test calculations, in which the interference effects between the atomic contributions are deliberately neglected, show a "flat" plateau, as it is known from high-order harmonic generation in atoms. It is shown that the characteristic modulations are present in ensembles of aligned fullerenes as well as randomly oriented ones. We further show that in the case of the larger fullerenes the radius can be determined from the positions of the interference minima in the high harmonic spectra using a spherical model.
|Journal||Physical Review A - Atomic, Molecular, and Optical Physics|
|State||Published - 3 Dec 2008|