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The vibrational structure of the Ag+NH3 complex has been investigated by single-photon zero kinetic energy (ZEKE) photoelectron spectroscopy. The intermolecular stretching mode with a frequency of 375 cm−1 is measured from the ZEKE spectrum, whereas the intermolecular bending vibration is not observed, in contrast to the A˜2E1/2–X˜2A1 electronic spectrum of the neutral AgNH3 complex [Miyawaki et al., Chem. Phys. Lett. 302 (1999) 354]. The ionization potential of AgNH3 was determined to be 47580 cm−1 (5.899 eV). [Copyright &y& Elsevier]

Threshold photoionization and pulsed-field-ionization zero-electron-kinetic-energy photoelectron spectra have been used to study the vibrational cooling of Cu–N(CH3)3 and the electronic cooling of Al–NH3 in helium and argon supersonic jets. The vibrational temperatures of Cu–N(CH3)3 are estimated to be ∼40 K in argon and ∼120 K in helium, whereas the electronic temperatures of Al–NH3 are about 20 and 80 K, respectively. Argon more efficiently cools the internal degrees of freedom of the metal systems, but helium provides additional spectroscopic information about the neutral molecules. The differences in the observed spectra have greatly facilitated spectral assignments for these complexes. [Copyright &y& Elsevier]