Our research focuses on the optical and electronic properties of nanoscale materials. Atomically thin two-dimensional materials, including graphene and ultrathin transition metal dichalcogenide crystals, are the subject of particular interest. Using optical and laser spectroscopic techniques, complemented by other physical probes, we examine the states of electrons in these systems and learn how they interact with one another, with lattice vibrations, and with other nearby materials. Our primary goal is understanding of fundamental physical properties, such as control of valley occupancy and excitonic states in these 2D systems, but we also are interested in the long-term potential of these materials and their combinations as heterostructures for novel electronic and photonic devices. An important tool for our research is femtosecond laser radiation, which permits direct observation of ultrafast dynamical processes, as well as access to nonlinear material response.