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.