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Tuesday, 31 July 2012

Malte: Strong field quantum control in CO2 in (1+2+3) steps

The polarisation dependence of double ionisation in CO2 and dissociative excitation of the parent ion
has been investigated experimentally via laser induced impulsive alignment. For the ?first time, the
recollision contribution to these channels is identifi?ed unambiguously and resolved angularly. This
is achieved by employing an elliptically polarised probe pulse, which maintains a main polarisation
direction while switching of? recollision. It was found that tunnel-ionisation from lower lying orbitals
in the neutral and thus higher lying excited states in the parent ion are involved in all of the investigated
processes, even at relatively low intensities. While CO+ is formed almost exclusively via tunnel ionisation from HOMO-2 followed by strong ?field excitation, recollision was found to be a signi?cant channel for O+ production. A strong polarisation dependence in both channels enables varying the associated branching ratios and demonstrates the possibility of strong fi?eld quantum control via the laser polarisation.