  We discuss a novel application of matter wave interferometry to characterize
the scalar optical polarizability of molecules at 532 nm. The interferometer
presented here consists of two material absorptive gratings and one central
optical phase grating. The interaction of the molecules with the standing light
wave is determined by the optical dipole force and is therefore directly
dependent on the molecular polarizability at the wavelength of the diffracting
laser light. By comparing the observed matter-wave interference contrast with a
theoretical model for several intensities of the standing light wave and
molecular velocities we can infer the polarizability in this first
proof-of-principle experiment for the fullerenes C60 and C70 and we find a good
agreement with literature values.
