Transition metal dichalgonides are 2D materials that have attracted significant attention because a single monolayer has a direct bandgap, whereas a bilayer, or more, is indirect. This transition is important for optics because direct gap materials emit light efficiently, whereas indirect gap materials do not. We will study these materials using optical coherent multidimensional spectroscopy at the diffraction limit. This method can remove the effects of sample heterogenity that results in inhomogeneous broadenng of resonances. We will start with currently available exfoliated samples, and then transition to studying samples grown by molecular beam epitaxy. The method is expected to reveal the presence of exciation induced dephasing and shifts, which indicate that many-body effects are present. These effects will be theoretically described using state-of-the-art theoretical and computational methods.