Electric deflection studies of rhodium clusters

The static electric dipole polarizabilities of rhodium clusters Rh-n, n=5-28, have been measured via a molecular beam deflection method. Uniform high-field beam deflections, indicative of induced polarization, were observed for all Rh-n except Rh-7 and Rh-10 which by contrast exhibited beam broadening and anomalously high effective polarizabilities. Analysis of the beam deflection profile of Rh-7 indicates that it possesses a permanent dipole moment of 0.24 +/- 0.02 D. Unlike the other clusters in the n=5-28 size range, the polarizability of Rh-10 is observed to decrease with increasing source temperature. We attribute this temperature dependence to paraelectric behavior, suggesting that Rh-10 is a fluxional molecule possessing a dipole moment that spatially fluctuates, uncorrelated with overall rotation.