  Charge transfer multiplet (CTM) theory is a computationally undemanding and
highly mature method for simulating the soft X-ray spectra of first-row
transition metal complexes. However, CTM theory has seldom been applied to the
simulation of excited state spectra. In this article, we extend the CTM4XAS
software package to simulate M2,3- and L2,3-edge spectra of excited states of
first-row transition metals and to interpret CTM eigenfunctions in terms of
Russell-Saunders term symbols. We use these new programs to reinterpret the
recently reported excited state M2,3-edge difference spectra of photogenerated
ferrocenium cations and propose alternative assignments for the electronic
state of the photogenerated ferrocenium cations supported by CTM theory
simulations. We also use these new programs to model the L2,3-edge spectra of
FeII compounds during nuclear relaxation following photoinduced spin crossover,
and propose spectroscopic signatures for their vibrationally hot states

Chemical Physics;Materials Science