Fig. 5: Comparison of the XPXP transient absorption experiment to an optically pumped transient XAS experiment.
From: Revealing core-valence interactions in solution with femtosecond X-ray pump X-ray probe spectroscopy
The thick red arrows correspond to dipole allowed transitions in the XPXP experiment and the thin red line represents the quadrupolar transitions probed in a transient XAS experiment. The red ovals indicate holes. XPXP transient absorption spectra measure the progressive blue-shifting of the 1s → 3p transition energy resulting from the unequal stabilization of 1s, 3p and 3d orbitals as a function of the number of holes in the t2g level. Here we probe core-excited 3p states with filled (a) and unfilled (b) and (c) 3dt2g shells and the resultant peaks are spectrally isolated around the Kβ emission energy peak and well-separated from the absorption edge.
