On the resonant coherent two-dimensional Raman scattering

A theoretical description of the resonant coherent two-dimensional Raman scattering (ReCOTRAS) process is presented. In comparison to the third-order coherent Raman scattering, ReCOTRAS measurement in frequency domain is a two-dimensional experiment probing two vibrational coherence states simultaneously. By using three external fields with frequencies and wave vectors as (ω₁,ω₂,ω₃) and (k₁,k₂,k₃), it is found that the ReCOTRAS field is generated with the frequency and the wave vector of 3ω₁-ω₂-ω₃ and 3k₁-k₂-k₃, respectively. It is shown that this experiment can provide two-dimensional vibrational spectrum that contains crucial informations on the vibrational mode-couplings in both the ground and the excited states. Unlike its off-resonant analogue, this method can be used to study the vibrational interactions in the electronic excited state.