SPECTROSCOPY IN THE 1-10 GHZ REGION WITH THE ARECIBO TELESCOPE

Several areas in molecular astrophysics and astrochemistry can be uniq uely studied by a large telescope in the 1 - 10 GHz range, despite the well-known advantages of the mm spectral range. Some atoms and molecu les can be observed only in the I - 10 GHz region, others are beat obs erved there, still others have special excitation effects there which elucidate important collision processes. Many species of most importan ce to astrochemistry occur in cold cloud cores where low-frequency stu dies can provide better abundances and high-resolution maps, both of w hich test chemistry models. Maser theories can be tested in a variety of species, including OH and CH, and several species as yet undetected and observable only at 1 - 10 GHz. Reliable abundances of OH and CH i n translucent clouds, obtainable only at Arecibo, are highly important to the astrochemistry of many species. Most molecules possessing a Ze eman effect are best observed in the 1 - 10 GHz region.