Stimulated X-ray Resonant Raman Spectroscopy of Conical Intersections in Thiophenol

The conical intersection dynamics of thiophenol is studied by computing the stimulated X-ray resonant Raman spectroscopy signals. The hybrid probing field is constructed of a hard X-ray narrowband femtosecond pulse combined with an attosecond broadband X-ray pulse to provide optimal spectral and temporal resolutions for electronic coherences in the level crossing region. The signal carries phase information about the valence-core electronic coupling in the vicinity of conical intersections. Two conical intersections occurring during the course of the S-H dissociation dynamics can be distinguished by their valence-core transition frequencies computed at the complete active space self-consistent field level. The X-ray pulse is tuned such that the Raman transition at the first conical intersection between ¹πσ* and 1¹ππ* involves higher core levels, while the Raman transition at the second conical intersection between ¹πσ* and S₀ involves the lowest core level in the sulfur K-edge.