Physical Chemistry is the study of macroscopic, atomic, particulate and sub-atomic phenomena in chemical systems. It is studied in terms of principles, practices, and concepts of physics. Energy, thermodynamics, motion, statistical mechanics and force are some common concepts of physics applied to this field. Quantum chemistry and spectroscopy are the two primary sub-fields of physical chemistry. The application of quantum mechanics to solve chemical problems falls under quantum chemistry. It provides tools to determine the shape of bonds, strength of the bonds, movement of nuclei and how light can be absorbed or emitted by a chemical compound. Whereas, spectroscopy is concerned with the interaction of electromagnetic radiation with matter. The objective of this book is to give a general view of the different areas of physical chemistry and its applications. Most of the topics introduced herein cover new techniques and applications of physical chemistry. This book will serve as a valuable source of reference for graduate and post graduate students.