Energy flow between spectral components in 2D broadband stimulated Raman spectroscopy

We introduce a general theoretical description of non resonant impulsive femtosecond stimulated Raman spectroscopy in a multimode harmonic model. In this technique an ultrashort actinic pulse createscoherences of low frequency modes and is followed by a paired narrowband Raman pulse and abroadband probe pulse. Using closed-time-path-loop (CTPL) diagrams, the response on both the redand the blue sides of the broadband pulse with respect to the narrowband Raman pulse is calculated, theprocess couples high and low frequency modes, which share the same ground state. The transmittedintensity oscillates between the red and the blue side, while the total number of photons is conserved.The total energy of the probe signal is periodically modulated in time by the coherence created in the lowfrequency modes.