title: Hot electron dominated rapid transverse ionization growth in liquid water.
abstract: Pump/probe optical-transmission measurements are used to monitor in space and time the ionization of a liquid column of water following impact of an 800-nm, 45-fs pump pulse. The pump pulse strikes the 53-μm-diameter column normal to its axis with intensities up to 2 × 10(15) W/cm2. After the initial photoinization and for probe delay times < 500 fs, the neutral water surrounding the beam is rapidly ionized in the transverse direction, presumably by hot electrons with initial velocities of 0.55 times the speed of light (relativistic kinetic energy of ~100 keV). Such velocities are unusual for condensed-matter excitation at the stated laser intensities.
authors.affiliation: Air Force Research Laboratory, Propulsion Directorate, 1950 Fifth St., Wright-Patterson AFB, Ohio 45433, USA. michael.brown@wpafb.af.mil
authors.forename: Michael S
authors.initials: MS
authors.lastname: Brown
authors.forename: Thomas
authors.initials: T
authors.lastname: Erickson
authors.forename: Kyle
authors.initials: K
authors.lastname: Frische
authors.forename: William M
authors.initials: WM
authors.lastname: Roquemore
mesh_terms: D004583:Electrons; D006358:Hot Temperature; D007477:Ions / Q000737:chemistry*; D007834:Lasers; D017711:Nonlinear Dynamics; D055095:Optics and Photonics / Q000379:methods; D014867:Water / Q000737:chemistry*
chemical_list: D007477:Ions; D014867:Water