Microwave Detection of Interstellar Formaldehyde

Abstract
Interstellar formaldehyde (H2CO) has been detected in absorption against numerous galactic and extragalactic radio sources by means of the 111-110 ground-state rotational transition at 4830 MHz. The absorbing regions often correspond in velocity with 18-cm OH features. H2CO is the first organic polyatomic molecule ever detected in the interstellar medium and its widespread distribution indicates that processes of interstellar chemical evolution may be much more complex than previously assumed.