1. What Is the Diffuse Universe?.- 2. Line Emission Processes.- 3. Collisional Excitation.- 4. Line Transfer Effects.- 5. Collisional Ionization Equilibrium.- 6. Continuum and Recombination Line Processes.- 7. Cooling Plasmas.- 8. Interstellar Shocks.- 9. The Theory of Photoionized Regions.- 10. Parameters of Photoionized Regions.- 11. Photoionizing Shocks.- 12. Interstellar Dust.- 13. Introduction to Astrochemistry.- 14. Thermal Phases of Diffuse Matter.- A. Physical Constants.- B. Useful Atomic Data.- B.1 Hydrogenic Spectra.- B.1.1 The Hydrogen Spectrum.- B.1.2 The Helium II Spectrum.- B.2 Abundances.- B.3 Collisional Excitation Data.- B.4 Ionization Potentials.- C. Continuum Data.- C.1 Free-Free Emission.- C.2 Total Free-Free Emission.- C.3 Two-Photon Emission.- D. Rotational Wave function Symmetry.- E. Answers to Selected Exercises.

The reference work on astrophysics to provide a comprehensive introduction to the physics of Interstellar Matter. The objective of the book is to show how physics can be applied to the understanding and diagnosis of the phase structure, the physical conditions and the chemical make-up and evolution of the interstellar medium. Unlike other textbooks in the field, here a more systematic approach has been adopted based on the authors' lecture course experience. It is aimed primarily at those undertaking post-graduate courses, or those doing advanced projects as part of honours undergraduate courses in physics or astrophysics.