Coherent control by a single phase shaped femtosecond laser pulse

Coherent control of molecular multiphoton ionization by a single phase shaped femtosecond laser pulse is reported. Electron and ion spectra of the sodium dimer are recorded in a molecular beam experiment and both show a strongly chirp- and pulse-length-dependent behavior. The measured spectra reveal that although for one chirp direction the population in all intermediate molecular states may be higher, the opposite chirp leads to a higher ionization yield. In addition, a strongly chirp-dependent photoionization of atomic sodium is observed.