Molecular Spectroscopy: Modern Research, Volume III is a collection of papers presented at the 40th Annual Molecular Spectroscopy Symposium, held at the Ohio State University. The contributors of this seven-chapter text cover the significant advances in molecular spectroscopic research and their application in chemistry. Chapters 1 and 2 discuss first the higher-order vibration-rotation interactions in molecules and then present formulas and an insight into the direction being taken in theoretical pursuits. Chapter 3 provides an extensive compilation of published intensity and collision broadening parameters derived from infrared spectra. This chapter also contains a detailed discussion using consistent notation of some of the methods commonly applied to extract such information from laboratory spectra. Chapter 4 examines a variety of laser systems and their application in investigations involving triatomic free radicals and ions, while chapter 5 considers the developments in the microwave spectroscopic studies on nonpolar molecules when their symmetry is reduced by isotopic substitution. Chapter 6 emphasizes the quasi-linear molecular problem to develop an appreciation of the symptoms of quasi-linearity and theoretical treatments thereof. This chapter also examines the increasing role of highly resolved spectra in the interpretation of various large-amplitude motions in molecules. Lastly, Chapter 7 describes the electric multipolar moments of hydrogen and its isotopes. Spectroscopists, chemists, and researchers will find this work invaluable.