This volume presents a collection of papers given at the 16th Mid -America Symposium on Spectroscopy held in Chicago, June 14-17, 1965. The Mid-America Symposium is sponsored annually by the Chicago Section of the Society for Applied Spectroscopy in cooperation with the St. Louis, Niagara Frontier, Cleveland, Detroit, lndianapolis, and Milwaukee Sections of the Society and the Chicago Gas Chromatography Discussion Group. Although we refer to this meeting as the Mid-America Symposium, it continues to attract attendance, interest, and inquiry from many parts of the world. Sessions on lnfrared, Raman, Ultraviolet, Visible, Emis- sion, Flame, Atomic Absorption, Nuclear Particle, Gamma Ray, Nuclear Magnetic Resonance, X-Ray Spectroscopy, Spec- troscopy, Spectrophosphorimetry, and Gas Chromatography provided interesting papers involving both applied and theo- retical principles. This volume continues a series of the Proceedings initiated in 1961 and is composed of a collection of 37 papers presented at this meeting. It is the opinion of the Symposium Committee that although not a complete account of the proceedings, publication of this collection as a reference is warranted. As editors of this volume, we wish to express our gratitude to the authors who gave their time and effort in submitting their manuscripts so that this volume could be published. The Symposium Committee, L. S. Gray, W. Baer, Vivian Biske, W. Los eki , M. S. Wang, F. Leahy, J. L. Ogilvie, B. D.