Fragmentation and Ionization Dynamics ofC60in Elliptically Polarized Femtosecond Laser Fields

Abstract

Ionization and fragmentation of ${\mathrm{C}}_{60}$ fullerenes is studied in elliptically polarized, intense fs laser fields at 797 nm [$I=(0.5–4.3)\times {10}^{14}\mathrm{W}{\mathrm{cm}}^{-2}$] and contrasted with ${\mathrm{Xe}}^{+}$, utilizing time-of-flight mass spectrometry. Very pronounced changes of parent and fragment ion yield as a function of ellipticity are observed. At lower intensities reduction of the ion yield for circular polarization establishes a coherent two-photon process connected with the key role of the $\mathrm{LUMO}+1(t_{1g})$ “doorway state” and multielectron dynamics. Comparison with the behavior at 399 nm corroborates this finding. At high intensities enhanced fragmentation is observed which is tentatively attributed to returning loops of electron trajectories by the combined action of the $\mathrm{C}_{60}{}^{+}$ field and the circular laser field.