Professor SAKABE, S., Associate Professor HASHIDA, M., et al.
    “Skinning of argon clusters by Coulomb explosion
    induced with an intense femtosecond laser pulse”

    Published in Physical Review A 74, 043205(2006)

    Progress in the development of intense femtosecond laser technology has opened up a new area of physics concerning the interaction of intense lasers and matter, that is, we can study the material physics in the intense optical field. Conventional intense laser of which pulse duration is order of 10ps-ns can only ionize any matter to be plasmas, and the interaction is not influenced by the matter characteristics, that is, merely laser-plasma interaction. With an intense femtosecond laser, intense optical field can be applied in the matter before the pulse energy is thermally transferred into the matter.

    Assoc Prof HASHIDA, M(left);
    Prof SAKABE,S(right)
    In our laboratory we are studying the physics and applications of such intense laser matter interactions, and as one topics laser nano- or micro-particle interaction is particularly interesting because the system is smaller than the wavelength of the laser used and the system is also an isolated solid system, into which electrons cannot be externally supplied. We have been studying intense femtosecond laser interactions with clusters.


    Vacuum chambers for laser-matter interaction


    By measuring the energy distributions of argon ions emitted from the laser irradiated argon clusters (100,000argon atoms), we found the new phenomena which is not observed by the nanosecond laser cluster interactions. With nano second pulse lasers, the cluster is thermally heated to be plasmas, and expanded isothermally and adiabatically, and as the result ions are emitted. However with intense femtosecond lasers, the electrons are stripped spontaneously from the cluster, and remaining ions argon cluster is exploded by strong Coulomb repulsive force (Coulomb explosion). Additionally it was found for the first time that by adjusting the laser intensity only the surface part of clusters can be Coulomb exploded and that the cluster can be skinned(Fig.1). It may have a potential as a fundamental technology for nano particle processing.


    Fig.1 Dynamics of the Coulomb explosion of argon clusters induced by intense femtosecond laser pulses.

    (Published in Physical Review A 74, 043205(2006))
    Intense Short-Pulse Laser System