title: Strong-field ionization of clusters using two-cycle pulses at 1.8 μm.
abstract: The interaction of intense laser pulses with nanoscale particles leads to the production of high-energy electrons, ions, neutral atoms, neutrons and photons. Up to now, investigations have focused on near-infrared to X-ray laser pulses consisting of many optical cycles. Here we study strong-field ionization of rare-gas clusters (103to 105atoms) using two-cycle 1.8 μm laser pulses to access a new interaction regime in the limit where the electron dynamics are dominated by the laser field and the cluster atoms do not have time to move significantly. The emission of fast electrons with kinetic energies exceeding 3 keV is observed using laser pulses with a wavelength of 1.8 μm and an intensity of 1 × 1015W/cm2, whereas only electrons below 500 eV are observed at 800 nm using a similar intensity and pulse duration. Fast electrons are preferentially emitted along the laser polarization direction, showing that they are driven out from the cluster by the laser field. In addition to direct electron emission, an electron rescattering plateau is observed. Scaling to even longer wavelengths is expected to result in a highly directional current of energetic electrons on a few-femtosecond timescale.
authors.affiliation: Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Bernd
authors.initials: B
authors.lastname: Schütte
authors.affiliation: Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Peng
authors.initials: P
authors.lastname: Ye
authors.affiliation: Max-Born-Institut, Max-Born-Strasse 2A, 12489 Berlin, Germany.
authors.forename: Serguei
authors.initials: S
authors.lastname: Patchkovskii
authors.affiliation: Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Dane R
authors.initials: DR
authors.lastname: Austin
authors.affiliation: Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Christian
authors.initials: C
authors.lastname: Brahms
authors.affiliation: Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Christian
authors.initials: C
authors.lastname: Strüber
authors.affiliation: Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Tobias
authors.initials: T
authors.lastname: Witting
authors.affiliation: Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.|Max-Born-Institut, Max-Born-Strasse 2A, 12489 Berlin, Germany.
authors.forename: Misha Yu
authors.initials: MY
authors.lastname: Ivanov
authors.affiliation: Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: John W G
authors.initials: JW
authors.lastname: Tisch
authors.affiliation: Department of Physics, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
authors.forename: Jon P
authors.initials: JP
authors.lastname: Marangos