Pumping liners for use in an apparatus for depositing a material on a work piece by chemical vapor deposition includes a plurality of unevenly spaced apertures are disclosed. Uneven spacing of the plurality of apertures produces a uniform flow of processing gases within a processing chamber with which the pumping liner is associated. Films of materials deposited onto a work piece by chemical vapor deposition techniques using disclosed pumping liners exhibit desirable properties such as uniform thickness and smooth and uniform surfaces.