Vibrational excitations in soft x-ray emission and core ESCA spectra of NH₃

Ab initio calculations are performed for the energy surfaces of the ground N 1s hole and 3a₁ hole states of ammonia in order to investigate the vibrational band profiles in its soft x-ray emission and core ESCA spectra. Both the N 1s and 3a₁ hole states are found to be planar. In comparison with the ground state, the N-H bond length is significantly shortened for the core hole state but relatively unchanged for the 3a₁ hole state. The results lead to a core ESCA spectrum dominated by a progression of closely spaced vibrational peaks of the pure bending mode and to a 3α₁ x-ray spectrum with excited stretch-bend combination bands.