IR-MPD of small silver clusters

Small silver clusters are very interesting for photography and Redox catalysis. They have size dependent optical properties and a strong interplay between their geometric and electronic structure, which has a discrete DOS. Despite the wide interest in small silver clusters, there is so far, besides for Ag3 and Ag4[1], no definitive (experimental) assignment of their geometry. Ion-mobility measurements on cationic silver clusters in the gas phase are available[2], but those measurements only provide cross sections. In addition, optical absorption spectra of Ag4 to Ag14 have been recorded, mapping their electronic excited states[3]. We have used FELIX to record the IR-MPD spectra of Ag_3+ to Ag_12+ in the far infrared (100-200 cm-1 spectroscopic wavenumbers). The silver clusters were produced in a laser vaporization cluster source and tagged with weakly bound argon, with Ar_n up to n=4. The measurements were performed at 90 K. By combining the experimental IR-MPD spectra with harmonic spectra for low energy isomers, as calculated by DFT, the structures of the silver clusters will be determined. [1] A. Fielicke et al. J. Phys. Chem. A 110, 8060 (2006) [2] P. Weis et al. Chem. Phys. Lett. 355, 355(2002) [3] Harb et al. J. Chem. Phys. 129, 194108 (2008)status: publishe