This book deals with the astrophysics and spectroscopy of the interstellar molecules. In the introduction, overview and history of interstellar observations are described in order to help understanding how the modern astrophysics and molecular spectroscopy have been developed interactively. The recent progress in the study of this field is briefly summarized. Furthermore, the basic knowledge of molecular spectroscopy, which is essential to correctly comprehend the astrophysical observations, is presented in a compact form.

To the memory of Gisbert Winnewisser

Gisbert, a talented scientist, an excellent supervisor, and a charismatic leader in the fields of molecular spectroscopy and astrophysics, passed away on March 21, 2011. This sad news arrived while we were busy proofreading the present volume. We are all in deep grief, but take some small comfort in the fact that we are now able to publish this book which he initiated.

K. Yamada