Selective ionization via different electronic pathways by optimal control demonstrated for 23Na39K/23Na41K

Selective optimization of different isotopomers in an ionization process with shaped fs-laser pulses is presented for (NaK)-Na-23-K-39/(NaK)-Na-23-K-41. By employing evolution strategies in a closed feedback loop a considerably high enhancement by a total factor of about 25 of one isotope compared to the other and reversed is measured. Surprisingly, vibrational levels of differing electronic states are utilized for the different isotopomer selections. Our approach generally allows to influence vibrational wave functions by coherent interaction with the corresponding spectral pulse components on the fs-time scale. (C) 2004 Elsevier B.V. All rights reserved.