The interaction of light with matter has been enormously success for probing both the static, and dynamics properties of materials. Non-linear spectroscopies can be classified as time-resolved, frequency-resolved, or an admixture of both.3-5 The non-linear spectroscopies discussed in this and the following chapters are time-resolved and hence require the use laser pulses, with preferably with short durations. Included in this category of electronically resonant, time-domain, non-linear spectroscopies are techniques such a photon echoes (PE), transient gratings (TG), and transient absorption (TA). Each of these spectroscopies are sensitive to specific properties of the system, and can be used to probe solvation dynamics. However, the three pulse photon echo stimulated peak shift (3PEPS) technique offers a more direct investigation of the underlying solvation dynamics and is the preferred technique for investigating non-polar systems.