Absolute measurement of the optical polarizability of C-60

We report on a new optical technique that uses light forces and a time-of-f light spectrometer to make absolute measurements of cluster polarizabilitie s. This is also the first accurate report of an ac polarizability measureme nt of a condensable cluster in the gas phase. We have determined the optica l polarizability of C-60 at the fundamental wavelength of a Nd:YAG laser (1 .064 mu m) to be alpha=79 +/- 4 Angstrom(3). (C) 2000 American Institute of Physics. [S0021- 9606(00)01038-2].