Double Ionization of N_2 and O_2 in Intense Laser Field
S. Voss, A.S. Alnaser, X.M. Tong, T. Osipov, C. Mahrajan, P. Ranitovic, B. Ulrich, B. Shan, Z. Chang, C.D. Lin, C.L. Cocke
(J. R. Macdonald Laboratory, Physics Department, Kansas State Univ., Manhattan, KS, 66506)
Different ionization processes can be identified by measuring the full momentum vectors of Coulomb exploding N^+ or O^+ fragments in coincidence using cold target recoil ion momentum spectroscopy (COLTRIMS). We measured high resolution kinetic energy release spectra and showed angular dependences for doubly ionized N_2 and O_2 molecules with laser peak intensities between 1 and 20 X10^1^4 W/cm^2. We found that the process of double ionization proceeds through well defined electronic states of the excited molecular dications. Using linear and circular polarized light, we identified two mechanisms for the production of theses states, rescattering and sequential ionization. By using 8 fs pulses, we observed that the internuclear distance can be frozen during the pulse.
This work was supported by the
Chemical Sciences, Geosciences and Biosciences Division,
Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy.
Submitted to DAMOP, May 2004 in Tucson, AZ.
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