INTERSTELLAR AND LABORATORY SPECTROSCOPY IN THE TERAHERTZ REGION

The field of interstellar molecules is reviewed with special considera tion of recent observational and technical advances in the shorter sub -millimeter wave region of the electromagnetic spectrum. At present mo re than 110 interstellar molecules have been identified in interstella r clouds and circumstellar envelopes. The more complex molecules are f ound in the dense cores which are often the sites of active star forma tion. These locations represent prime targets for the search of larger molecules such as glycine. However, in the list of detected interstel lar molecules many simple hydrides are still missing, including, e.g., SH, PH, PH2, etc., which constitute the building blocks of larger mol ecules. With the technological opening of the terahertz region (nu con gruent to 1 THz corresponds to lambda congruent to 0.3 mm) to both lab oratory and interstellar spectroscopy, great scientific advances are t o be expected. Amongst these will be the direct detection of the lowes t rotational transitions of the light hydrides, the low energy bending Vibrations of larger (linear) molecules, and possibly the ring-pucker ing motion of larger ring molecules like the polycyclic (multiring) ar omatic hydrocarbons. (C) 1997 Elsevier Science B.V.