High-charge Coulomb explosions of clusters in ultra-dense deuterium D(-1)

Laser-induced Coulomb explosions of clusters D(N) in ultra-dense deuterium D(-1) show a broad spectrum of fragmentation processes. For small clusters D(3) and D(4) symmetric fragmentation processes are often observed. Experiments now show that these clusters fragment by maximum-charge processes, like D(4)(4+) -> 4D(+), each fragment leaving with 945 eV kinetic energy. This is the case even at low laser pulse intensities of <10(12) W cm(-2). The facile laser field ionization of these clusters is probably caused by their small size. Such high-charge processes seem to be most common in the superfluid condensed phase. A centrifugal stretching in the clusters is observed, giving 5-8% longer D-D bonds at higher average laser intensity, probably at J <= 3. Rotational excitation of D(2)(+) fragments is often apparent at similar J values. This requires strong bonding between the two deuterons, predicted to be close to 700 eV due to strong exchange interaction. (C) 2011 Elsevier B.V. All rights reserved.