Insights on the Dissociation Dynamics of Ammonia Through Core-Hole Molecular Frame X-Ray Photoelectron Angular Distributions*

We present experimental and theoretical results for the angular dependence in the body frame of electrons ejected from the core orbitals of ammonia that verify the imaging effect predicted earlier by which the molecular frame photoelectron angular distributions (MFPADs) for removing an electron from a 1s orbital effectively image the geometry of a class of molecules. Ammonia with a 1s vacancy undergoes double Auger decay to produce, in one channel, 3 protons and a neutral N atom, allowing the determination of the MFPAD in a four-particle coincidence experiment. Calculations have predicted an imaging effect in a class of molecules whereby the electron ejected by core photoionization has the tendency to follow molecular bonds if averaged over directions of polarization of the incident X-ray beam. We combine experimental results to quantum chemistry calculations to investigate the dissociation dynamics of ammonia after double Auger decay. Our measurements employ the COLTRIMS method and the calculations were performed with the Complex Kohn Variational method.