  The identification of the decay pathway of the nucleobase uracil after being
photoexcited by ultraviolet (UV) light has been a long standing problem.
Various theoretical models have been proposed but yet to be verified. Here we
propose an experimental scheme to test the theoretical models by a combination
of ultrafast X-ray spectroscopy, X-ray diffraction and electron diffraction
methods. Incorporating the signatures of multiple probing methods, we
demonstrate an approach to identify the pathway of the geometric and electronic
relaxation of the photoexcited uracil molecule.
