Magic numbers of gold clusters stabilized by PVP.

We applied matrix-assisted laser desorption/ionization (MALDI) for mass analysis of Au clusters stabilized by poly(vinyl-pyrrolidone) (PVP) and discovered a series of magic numbers for Au cluster size: 35 +/- 1, 43 +/- 1, 58 +/- 1, 70 +/- 3, 107 +/- 4, 130 +/- 1, and 150 +/- 2. Magic numbers smaller than approximately 70 agree with those of free Au clusters and can be explained qualitatively by the electronic shell model. In contrast, magic numbers larger than approximately 100 are obviously different from those of the free clusters. We suggest that the deviation from the electronic shell model is due to perturbation of the electronic and/or geometric structures caused by interaction with PVP.