High-resolution infrared spectroscopy of HCN-Agn (n = 1-4) complexes solvated in superfluid helium droplets.

High-resolution infrared spectroscopy has been used to determine the structures, C-H stretching frequencies, and dipole moments of the HCN-Agn (n = 1-3) complexes formed in superfluid helium droplets. The HCN-Ag4 cluster was tentatively assigned based upon pick-up cell pressure dependencies and harmonic vibrational shift calculations. Ab initio and density functional theory calculations were used in conjunction with the high-resolution spectra to analyze the bonding nature of each cluster. All monoligated species reported here are bound through the nitrogen end of the HCN molecule. The HCN-Agn complexes are structurally similar to the previously reported HCN-Cun clusters, with the exception of the HCN-Ag binary complex. Although the interaction between the HCN and the Agn clusters follows the same trends as the HCN-Cun clusters, the more diffuse nature of the electrons surrounding the silver atoms results in a much weaker interaction.