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 (omega(1),omega(2),omega(3)) and (k(1),k(2),k(3)), it is found that the ReCOTRAS field is generated with the frequency and the wave vector of 3 omega(1)-omega(2)-omega(3) and 3k(1)-k(2)-k(3), 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. (C) 1998 American Institute of Physics. [S0021-9606(98)02637-3].