  High energy (C, D) excitons possess remarkable influence over the optical
properties of layered transition metal dichalcogenides (TMDCs) and
comprehensive understanding of these may have revolutionary effect on 2D
opto-electronic devices. Herein, we employed transient absorption spectroscopy
to monitor the underlying photo-physical processes involved with C, D excitons
in few layer WS2. We observed a strong inter-valley coupling across the
momentum space. C, D dynamics were significantly slower as compared to
canonical A, B excitons, as a consequence of the indirect Lambda-Gamma
relaxation in C, D, unlike K-K direct combination in A, B. Optical behaviour of
D excitons was found to be more like A, B, contrary to C, which enjoy unique
band nesting effects. Also, C excitons do not hold in any specific position of
the momentum space, rather depends upon the photon energy. All these excitons
immensely influence each other irrespective of the excitation energy.
