TITLE: The light-force method for measuring polarizabilities and a measurement of the optical polarizability of C₆₀ at 1.064 mm

SPEAKER: Adam Ballard,

TIME: Thursday Sept. 20, 2001 at 4 PM

PLACE: George P. Williams, Jr. Lecture Hall, (Olin 101)

I will describe in detail an experimental technique known as the light-force, which can be used to determine the frequency dependent polarizability of an atom or cluster in the gas phase. This method is unique in that it can in principal be applied to both neutral and ionized clusters alike with only modest changes in technique.  This method is also attractive in that it is an absolute method and does not require the use of a reference atom to be accurate. I also report on a measurement of the polarizability of C₆₀ clusters, which was completed using this method. To date this is the most accurate polarizability measurement of any cluster larger than two atoms. Using this method, the optical polarizability of C₆₀ at 1.064 mm (2.82 x 10¹⁷Hz) was found to be 79 ± 4 ų.