We present the design of a highly efficient, pulsed ammonia laser which is optically pumped by a commercial TEA CO2 laser and is line tunable in the spectral range of 780-930 cm(-1). The power, spectral, and temporal characteristics of the laser have been investigated for different configurations of the optical cavity. Using a stable resonator, the laser operates with an efficiency of 24% (940 mJ) in a multiline configuration and 16.5% on a single line. Changing the resonator to an unstable configuration produces a diffraction limited output on a single line with an efficiency of 13%. These output characteristics make this laser suitable for experiments in the field of infrared multiphoton dissociation. (C) 1998 American Institute of Physics. [S0034-6748(98)01712-2].