Resonant inelastic x-ray scattering (RIXS) provides remarkable opportunities to interrogate
ultrafast dynamics in liquids. Here we use RIXS to study the fundamentally and practically
important hydroxyl radical in liquid water, OH (aq). Impulsive ionization of pure liquid water
produced a short-lived population of OH (aq), which was probed using femtosecond x-rays
from an x-ray free-electron laser. We find that RIXS reveals localized electronic transitions
that are masked in the ultraviolet absorption spectrum by strong charge-transfer transitions …

… EE-CCSD calculations for the hydroxyl radical employ the UHF reference. …
arrangements of the OH radical with a nearby water molecule results in charge-transfer tran- …
If the products of the transition moments between the offresonant core states with the initial
and final states are large, off-resonant core states cannot be omitted in the few-state model.
This, however, is not the case for our model structures. Second, the denominators in the sum-over-states
terms for the low-lying valence intermediate states are order(s) of magnitude larger than that …