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We performed time-of-flight (TOF) spectroscopy on a jet of rare gas clusters using light pulses at λFEL = 32 nm produced by the FLASH VUV freeelectron-laser (Hamburg, Germany) with a maximum peak power density of about 3 × 1013 W/cm2 at the sample. Energy deposition on the clusters was found to be strongly dependent on lambda and much more efficient in the VUV than in the IR and visible spectral range. We observed multiple ionization of rare gas atoms coming from clusters; the latter fragment completely upon absorption of a single pulse. We have also measured high quality photoelectron spectra. Small angle soft X-ray scattering (SAXS) from a single light pulse (λFEL = 32 nm), was recorded with high signal to noise ratio for very large (Natoms 3 × 106) Argon clusters.

Publisher Summary This chapter presents notions, facts, and findings on C60 and the fullerenes. The chapter discusses basic terminology and concepts from the area of atoms and molecules in strong fields. Some experimental aspects of studying molecules in intense, short pulse laser fields are addressed. The chapter also explains the ionization process, charge states, and fragmentation after short pulse laser interaction with C60 as observed by mass spectroscopy. The intensity dependence of these processes and compares saturation intensities for the ionization processes with simple atomic systems is addressed in the chapter. Further, the above threshold ionization (ATI) observed in photoelectron spectra at various short pulse laser intensities are discussed and compared with the recent theoretical results. Theoretical comparison leads to a critical discussion of the primary excitation mechanism in an intense laser pulse. The chapter also discusses the band structure model in condensed matter, that is, for a semiconductor in the case of C60. The chapter illustrates this with an example: the non-resonant excitation of Rydberg states in C60. Further, the fast fragmentation processes of C60 beyond the established statistical fragmentation processes known to occur on the ns to μs time scale are addressed.