Broad angular distributions have been observed for XeCl laser ablation plumes used in the deposition of YBa2Cu3O7−&dgr;thin films. Distributions (inferred from film thickness) and film stoichiometry were measured as a function of laser fluence, beam shape, and oxygen pressure. Parallel to the long axis of the laser spot, plumes exhibited a cos3.5(&thgr;) spread and composition varied with angle; in the perpendicular direction, more diffuse [cos1.5(&thgr;)] plume distributions were associated with stoichiometric deposition. The observed phenomena are consistent with formation of a Knudsen layer near the target surface.