26 research outputs found
Determining Orientations of Optical Transition Dipole Moments Using Ultrafast X-ray Scattering
Identification
of the initially prepared, optically active state
remains a challenging problem in many studies of ultrafast photoinduced
processes. We show that the initially excited electronic state can
be determined using the anisotropic component of ultrafast time-resolved
X-ray scattering signals. The concept is demonstrated using the time-dependent
X-ray scattering of <i>N</i>-methyl morpholine in the gas
phase upon excitation by a 200 nm linearly polarized optical pulse.
Analysis of the angular dependence of the scattering signal near time
zero renders the orientation of the transition dipole moment in the
molecular frame and identifies the initially excited state as the
3p<sub><i>z</i></sub> Rydberg state, thus bypassing the
need for further experimental studies to determine the starting point
of the photoinduced dynamics and clarifying inconsistent computational
results