  Excitations between localized 3d states of transition metal ions within
crystalline solids, commonly known as d-d transitions, play a pivotal role in
diverse phenomena across solid state physics, materials science, and chemistry.
These transitions contribute to the coloration in transition metal oxides,
catalytic processes on oxide surfaces, and high-temperature superconductivity.
They also couple optical excitation to quantized collective phenomena such as
phonons and magnons in magnetic systems. Until now, an experimental method to
unravel the complex quasiparticle dynamics associated with d-d transitions has
remained elusive. We bridge this gap by demonstrating that d-d transitions can
be distinctly traced in momentum space and time using time- and angle-resolved
photoelectron spectroscopy (trARPES). Through this approach, we can assign
specific momentum-dependent characteristics and elucidate the decay mechanisms
of specific d-d transitions in FePS$_{3}$, a two-dimensional van der Waals
antiferromagnet with a rich array of quantum phenomena stemming from d-d
transitions. This study pioneers the use of ARPES in probing the dynamics of
d-d transitions across a wide spectrum of solid-state systems.
