Ag5 is a planar trapezoidal molecule

The Raman spectrum of Ag-5, mass-selected from a sputtered jet of silver cluster ions, neutralized and matrix isolated in solid argon, is reported. Analysis of the frequencies and intensities of the 7 vibrational modes recorded suggests unequivocally that the molecule has a planar trapezoidal structure. No other reasonable structure is consistent with the observations. Nor is there evidence for more that one structure coexisting with the planar trapezoid. The observation is in accord with the conclusions of most quantum computations on Ag-5. The silver pentamer is found to photofragment into the dimer and trimer when irradiated with 458 or 466 nm laser light. (C) 1998 American Institute of Physics. [S0021-9606(98)00209-8].