Far infrared emission spectroscopy is a powerful technique for the measurement of a number of molecules that are important in stratospheric (i.e., ozone layer) chemistry. The technique is particularly applicable to polar molecules with large, hydrogenic rotational constants [Chance et al., 1985]. These molecules include diatomics (HCl, HF, HBr, and OH), and nearly symmetric prolate molecules with large perpendicular components of their dipole moments (HOCl, H2O2, and HO2). They have strong rotational spectra in the far infrared that persist to sufficiently high energy (80 cm-1 and above) that their spectra do not suffer great interference from the rotational lines of H2O and O3 which dominate the far infrared atmospheric spectrum. Thus, this type of molecule can be measured with great sensitivity from about 80 to 200 cm-1.