Volume 109 in the prestigious Advances in Chemical Physics Series, edited by Nobel Prize winner Ilya Prigogine, and renowned authority Stuart A. Rice, continues to report recent advances in every area of the discipline. Significant, up-to-date chapters by internationally recognized researchers present comprehensive analyses of subjects of interest and encourage the expression of individual points of view. This approach to presenting an overview of a subject will both stimulate new research and serve as a personalized learning text for beginners in the field.