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Summary form only given. I report generation of tunable cw infrared at 11.5 microns by difference frequency mixing using two room-temperature diode lasers with 20 mW at 807 nm and 100 mW at 868 nm in a 5-mm-long GaSe crystal. The infrared was smoothly tuned by current and temperature tuning the room-temperature diode lasers about 2 cm/sup -1/ without mode hops, as observed by scanning a germanium etalon with a 12.5-GHz free spectral range. The tunable infrared was used to scan an identified set of five ammonia absorption lines centered at 867.8 cm/sup -1/ (11.52 micron) using a 10-cm-long gas transmission cell at 5 Torr and a liquid nitrogen cooled HgCdTe detector.