Liquid immersion interference lithography at 157 nm has been used to print gratings of 27 nm half pitch with a fluorine-doped fused silica prism having index of 1.66. In order to achieve these dimensions, new immersion fluids have been designed and synthesized. These are partially fluorinated organosiloxanes with indexes up to 1.5. Their absorbance is on the order of 0.4/mu m (base 10), enabling the use of liquid films with micron-size thickness. To utilize these serniabsorptive fluids, an immersion interference printer has been designed, built, and implemented for handling micron-scale liquid layers. (c) 2006 American Vacuum Society.