K-edge x-ray-absorption spectroscopy of laser-generated Kr + and Kr 2+

observed from the dependence of the 1s → 4p resonant x-ray absorption cross section on the angle between the laser and x-ray polarization vectors 6. Theoretical analysis of the experiment demonstrated that it is essential to include spinorbit coupling in models of strong-field ionization of Kr 11. The polarization dependence of the 1s → 4p resonance and the variable pump-probe delay were also used to follow the time evolution of the collective Kr + alignment in the e � -Kr + plasma produced by laser ionization 7. That paper presented a theoretical model that accounts for the timedependent dealignment and also reported on the effects of imposing an external magnetic field.