Zero electron kinetic energy photoelectron spectroscopy and density functional theory calculations of gallium-methylamine complexesThe gallium complexes were produced in pulsed molecular beams and studied with zero electron kinetic energy ͑ZEKE͒ photoelectron spectroscopy. Intermolecular vibrational frequencies and adiabatic ionization potentials ͑IPs͒ were obtained from ZEKE spectra. Ground electronic states were identified by combining the ZEKE spectra with quantum chemical and Franck-Condon calculations. Ga-NH 3 has an IP of 40 135 cm Ϫ1 and metal-ligand stretching frequencies of 270 cm Ϫ1 ( s ϩ ) in the ion and 161 cm Ϫ1 ( s ) in the neutral. The IP of Ga-NH 2 CH 3 is 39 330 cm Ϫ1 , and the vibrational frequencies are 93 cm Ϫ1 ( b ) for the Ga-N-C bending, 124 cm Ϫ1 ( b ϩ ) for the Ga ϩ -N-C bending, and 299 cm Ϫ1 ( s ϩ ) for the Ga ϩ -N stretching. The strength of the galliummethylamine binding is stronger than that of the gallium-ammonia. The ground state of Ga-NH 3 is 2 AЈ(C s ) and that of Ga ϩ -NH 3 is 1 A 1 (C 3v ). In contrast, Ga-NH 2 CH 3 has two doublets, 2 AЈ and 2 AЉ(C s ), with virtually the same energies, whereas Ga ϩ -NH 2 CH 3 has a 1 AЈ(C s ) ground state.