About the Book : There are several books on Molecular Spectroscopy that treat the subject in considerably less space than this comprehensive text. Moreover, most of them include a great deal of introductory theory, which has been omitted from the larger book because of space considerations. The net result is that the book contains the real content of Molecular Spectroscopy. The purpose in A Handbook of Molecular Spectroscopy, is to meet the needs of teachers who present this subject to students who do not have the time or perhaps the inclination to pursue it in depth, but who may also require explicit coverage of basic topics. This book therefore introduces material in an elementary fashion, and presents only the main facts. Molecular Spectroscopy sans facts, as present in other books, is like a page of music with no instrument to play it on. One can appreciate the sound of music without knowing anything of musical theory although of course one's appreciation is enhanced by knowing some theory. However, a book of musical theory, even if it is illustrated by audible snatches of themes and a few chord progressions, is quite unlike the hearing of a real composition in its entirety. We believe that a student who has read a book on 'Molecular Spectroscopy' that consists almost entirely of theory and so-called principles, with but sporadic mention of the hard facts (only when they "nicely" illustrate the "principles") has not, in actual fact, had a course in Molecular Spectroscopy. This book avoids the current trend towards this way of teaching students who are not expected to specialise in the subject, and believe that even the non-specialist ought to get a straight dose of the subject.