This rigorous and engaging book presents the basic theories underlying spectroscopy while incorporating modern viewpoints of practical utility in spectroscopy research. Written in a clear, jargon-free style, it covers the quantum mechanical theoretical basis of spectroscopy, modern innovations in spectroscopy theory, such as time-dependent theory, and practical applications of spectroscopy research, including the influence of condensed phases. Begins with a brief review of quantum mechanical principles, then moves on to such areas as the properties of light, bulk electric and magnetic properties of matter, fundamental theories of spectroscopic techniques, experimental arrangements, and finally applications of the electromagnetic spectrum. Studies the time-dependent theoretical approach to interpret frequency domain spectra, allowing readers to focus on the dynamic response of the system. Provides consistent and reasonable notation throughout, frequently uses thought experiments to help readers visualize a physical situation. and poses probing questions in order to stimulate independent thinking and prompt readers to consider potentially paradoxical predictions of theory. For spectroscopists, laser technicians, analytical and physical chemists, and physicists.