Knowledge Bank

Zero electron kinetic energy (ZEKE) photoelectron spectroscopy was used to study the electronic spectra of metal-diammonia and its deuterated species. The adiabatic ionization potential of the copper complex was measured to be $29532cm-1$, a shift of more than a factor of two relative to that of the copper atom ($62317cm-1$); deuteration further decreased the ionization potential of the complex by $219cm-1$ due to the shift of the zero point vibration energies. Furthermore, the ZEKE spectra revealed the copper-ammonia vibrations and ammonia torsion. For example, in $Cu(NH3)2$ the metal ion -ligand symmetric stretching and bending frequencies were measured to be 436 and $139cm-1$, whereas the $NH3$ torsion was determined as $32cm-1$.