In this dissertation, we describe a spectroscopic study of metal clusters and metal-ligand complexes using pulsed field ionization zero kinetic energy (PFI-ZEKE) photoelectron spectroscopy and mass analyzed threshold ionization (MATI) spectroscopy. Vibrational resolved spectra of sodium dimer, Na•NH₃, Na•(NH₃)₂ are presented. These spectra provide a direct measurement of the ionization...