Ionization of methane in strong and ultrastrong relativistic fields.
The photoionization of methane is reported for intensities up to 10(19) W/cm2 with linear and circular polarized light. While fragmental ions (e.g., CH3+, CH+, C+, C2+) created from 10(14) W/cm2 to 10(15) W/cm2 are formed by Coulomb explosion, ionization to form C3+ and C4+ involves Coulomb explosion and tunneling ionization. In ultrastrong fields, removal of a carbon K-shell electron from methane proceeds via tunneling and rescattering ionization, without the influence of molecular channels. Photoelectrons from methane at 10(19) W/cm2 extend up to kinetic energies of 0.6 MeV.
Physics and Astronomy Department, University of Delaware, Newark, Delaware 19716, USA.
Sasi
S
Palaniyappan
Rob
R
Mitchell
Rob
R
Sauer
Isaac
I
Ghebregziabher
Samantha L
SL
White
M F
MF
Decamp
B C
BC
Walker