Complete determination of relaxation parameters from two-dimensional Raman spectroscopy

Using the model of a weakly-anharmonic, underdamped oscillator coupled to a bath, we demonstrate that the 2D time-resolved Raman signal carries information about the population decay T₁, the homogeneous dephasing T₂, and the inhomogeneous dephasing T₁ relaxation timescales. We distinguish between two projections of the 2D signal: first, the echo signal, which is stretched in the diagonal direction decays with T₂, and the second which is stretched along one axis is related to the population relaxation and decays with T₁. The width of both signals reflects T₁. Equations of motion for vibrational coherence and population variables are employed in these calculations.