. Double pulse SOFSRS scheme, where the two actinic pulses are separated by time t, corresponding to one period of oscillation of a phonon mode. The actinic beam is offset using a pair of scanning galvo mirrors. Following this excitation, the Raman pump and probe arrive after ∆𝑡 and stimulate Raman scattering. B. Optical image of pentacene crystal with inset displaying photoexcitation locations. (0, 0) denotes full overlap between the actinic and probe beams, and (2.7, 0) and (0, 2.7) correspond the actinic offset from the probe by 2.7 µm. C. Pentacene crystal structure as rendered in Mercury. D. Pentacene phonon mode Raman spectrum. In order to identify the functional role of phonon modes in exciton transport, we employ double pulse excitation spatially offset femtosecond stimulated Raman spectroscopy (SOFSRS). Femtosecond stimulated Raman spectroscopy (FSRS) measures the excited state structure of a molecular system using a single photoexcitation, or actinic, pulse followed by Raman pump and probe pulses. Our group recently developed SOFSRS, which spatially offsets the actinic pulse from the Raman pump and probe using galvanometric scanning mirrors (Fig. ), thereby tracking how the vibrational spectrum evolves during exciton transport in real time. SOFSRS combines the high structural specificity of FSRS with the imaging capabilities of TAM, allowing us to gain greater insights into the interplay of molecular and crystal structure with complex exciton transport dynamics. Here, we demonstrate the first use of a double pulse excitation SOFSRS to monitor the role of phonon modes in crystalline pentacene exciton transport and unambiguously distinguish between spectator and driving modes.