3 research outputs found
Correlation dynamics between electrons and ions in the fragmentation of D molecules by short laser pulses
We studied the recollision dynamics between the electrons and D ions
following the tunneling ionization of D molecules in an intense short pulse
laser field. The returning electron collisionally excites the D ion to
excited electronic states from there D can dissociate or be further
ionized by the laser field, resulting in D + D or D + D,
respectively. We modeled the fragmentation dynamics and calculated the
resulting kinetic energy spectrum of D to compare with recent experiments.
Since the recollision time is locked to the tunneling ionization time which
occurs only within fraction of an optical cycle, the peaks in the D kinetic
energy spectra provides a measure of the time when the recollision occurs. This
collision dynamics forms the basis of the molecular clock where the clock can
be read with attosecond precision, as first proposed by Corkum and coworkers.
By analyzing each of the elementary processes leading to the fragmentation
quantitatively, we identified how the molecular clock is to be read from the
measured kinetic energy spectra of D and what laser parameters be used in
order to measure the clock more accurately.Comment: 13 pages with 14 figure
Effect of amniotic fluid on cationic lipid mediated transfection and retroviral infection
In preparation for foetal gene therapy by intra-amniotic gene application, we have investigated the effect of amniotic fluid on several gene transfer systems. In vitro lipofection of embryonically derived 3T3 cells by several of the tested cationic lipids decreases in the presence of human amniotic fluid, while two formulations, Lipid 67 and Tfx-50, remain highly active. As some body fluids are known to inactivate most retroviral vectors, we investigated the influence of amniotic fluid on the efficiency of infection of 3T3 cells by murine leukaemia virus (MoMLV)-based vectors, including amphotropic and ecotropic retrovirus, and a vesicular stomatitis virus G (VSV-G) glycoprotein pseudotyped retroviral vector. All showed a decrease of infectivity from 21 to 56% in the presence of amniotic fluid. The ecotropic retrovirus is the most infectious under normal conditions as well as in amniotic fluid. Our results suggest that intra-amniotic injection may allow efficient gene transfer using either amniotic fluid-resistant cationic lipids or ecotropic retroviral vectors in a murine in vivo model for foetal gene therapy. The VSV-G-pseudotyped vector, although displaying a decrease of infectivity, remains of great interest for gene delivery, because of its broad host range and because of the high virus titers achievable. Finally, a baculovirus-based vector shows no decrease of its infectivity and does not seem to be affected by amniotic fluid but has only low infectivity on the tested foetal fibroblast cell line