Femtosecond time-resolved four-wave mixing spectroscopy in iodine vapour

Femtosecond time-resolved four-wave mixing (FWM) spectroscopy is performed using degenerate laser frequencies in order to investigate molecular dynamics in iodine molecules in the gas phase. It is demonstrated that by varying the timing as well as the wavenumber position for the signal detection different dynamics can be accessed. This is due to a selection of contributions (e.g. described by Feynman diagrams) to the nonlinear polarization of the process. The wave packet dynamics of the electronic excited B as well as the X ground state of iodine can be monitored by degenerate FWM, coherent anti-Stokes Raman scattering or coherent Stokes Raman scattering (CSRS) processes all included in the same experiment.