The changes in depletion magnitude along the fast and slow axes are the result of modification of exciton transport by the 91 cm -1 phonon mode. The depletion magnitude does not change at the fully overlapped photoexcitation position, which indicates that the overall population of excited states does not change with amplification of the 91 cm -1 phonon mode. The overlapped region contains contributions from excitons travelling in both the fast and slow axes, and therefore cannot distinguish between changes to population along each axis. Because the overall population does not change relative to the single pulse at (0, 0), the differences between the fast and slow axis depletion magnitude result from modification of the exciton transport dynamics. We would expect that the increase in the slow axis signal would be equivalent to the decrease in the fast axis, but instead we observe an increase in depletion magnitude nearly twice as large along the slow axis. The nearly 40% signal increase along the slow axis likely does not directly reflect the true excited state population change due to the change in resonance of the triplet state as previously discussed.