This book teaches the analyst why it is advantageous to obtain vibrational data under different physical phases. Molecular vibrations are affected by change in physical phase, and knowledge of how certain molecular vibrations are affected by change in the chemical environment improves the analyst's ability to solve complex chemical problems. This book is invaluable for students and scientists engaged in analytical and organic chemistry, since application of IR and Raman spectroscopy is essential in identifying and verifying molecular structure. This reference provides analysts with information that enables them to acquire the maximum amount of information when sampling molecular vibrations via IR and Raman spectroscopy. It explains why it is advantageous to obtain vibrational data under different physical phases. It compiles many vibrational studies into a single. It lists group frequencies in different physical phases. It reveals that some group frequencies are more affected than others by changes in the physical phase. It demonstrates that in-phase and out-of-phase vibrations of the same functional group are not equally affected. It describes how solute-solvent complexes differ with changes in the solvent system. It shows that the amount of Fermi resonance between a fundamental vibration and a combination or overtone is altered with change of physical phase. It is written by an internationally recognized expert.