• time and frequency resolved;
  • four-wave mixing;
  • femtosecond;
  • rotational recurrences


Simultaneous time and frequency detection in off-resonant femtosecond degenerate four-wave mixing (fs-DFWM) experiments displays spectral features that are covered in standard, nondispersed, frequency-integrated measurements. The application of laser fields with finite bandwidths, narrower than or comparable to the rotational Raman bands, affects the observed coherent signals. Information available from such experiments is split between the time and frequency domains and an improved measurement necessitates a combined detection. Rotational recurrences of oxygen (O2), measured by dispersed fs-DFWM at room temperature, exhibit spectral characteristics, using 800-nm laser pulses with ∼100 fs duration. Analysis of the detected signals in both dimensions incorporating temporal and spectral trends can assist in the extraction and interpretation of chemicophysical quantities from the experiment. The dispersed recurrent signals are in accordance with simulations. Copyright © 2011 John Wiley & Sons, Ltd.