  We demonstrate that a bichromatic standing-wave laser field can exert a
significantly larger force on a molecule than ordinary radiation pressure. Our
experiment measures the deflection of a pulsed supersonic beam of CaF molecules
by a two-frequency laser field detuned symmetrically about resonance with the
nearly closed $X (v=0) \rightarrow B (v'=0)$ transition. The inferred force as
a function of relative phase between the two counterpropagating beams is in
reasonable agreement with numerical simulations of the bichromatic force in
this multilevel system. The large magnitude of the force, coupled with the
reduced rate of spontaneous emission, indicates its potential utility in the
production and manipulation of ultracold molecules.
