edited by M S Child (University of Oxford)

The study of molecular Rydberg states is a rapidly growing interdisciplinary field. This valuable report, constituting the proceedings of a Royal Society Discussion reflects the state of the present theoretical knowledge, and includes an introductory chapter for the non-specialist. The material is organised to bring out the wealth of observable effects. Some states commonly lead to competitive predissociation and autoionization, with relevance to atmospheric and astrophysical processes. Others, with higher angular momenta, have much longer lifetimes and high electronic degeneracies, which on one hand pose subtle problems for experimental interpretation, and on the other act as reservoirs for a class of remarkably stable so-called ZEKE states. New experiments to clarify the formation mechanism of such states, and to exploit their properties, are described. The interplay between “quantum defect” and “ab initio” aspects of the theory is also underlined.

• The Nature of Molecular Rydberg States (M S Child)
• Solved and Unsolved Problems of Near-Threshold Spectroscopy of N₂ and CO (K P Huber)
• Rydberg States of Triatomic Hydrogen (C H Greene & J A Stephens)
• Spectroscopy and Dynamics of the Rydberg States of C₂H₂ and Their Relevance to Astrophysical Photochemistry (N Shafizadeh et al.)
• Near Ultraviolet Photolysis of Ammonia and Methylamine Studied by H Rydberg Atom Photofragment Translational Spectroscopy (M N R Ashfold et al.)
• The Role of Rydberg States in Dissociative Recombination, as Revealed by Ion Storage Ring Experiments (L Carata et al.)
• Time and Frequency Resolved ZEKE Spectra and the Interseries Dynamics of High Molecular Rydberg States (F Remacle)
• and other papers