PHOTOACOUSTIC STUDY OF VIBRATIONAL OVERTONES IN POLYATOMIC MOLECULES

Author Institution: The Standard Oil Company (Ohio) Corporate, Research CenterIntracavity gas phase photoacoustic spectroscopy is used to investigate the near-IR and visible overtone spectra of various polyatomic molecules. This report summarizes some of our current data. The description of overtone structure is based on the local mode model. It is known that the influence of the conformational environment on the X-H oscillators (X=C,O,N) can be easily observed in the overtone spectra for the X-H stretching vibration. This sensitivity to molecular geometry may provide important new information concerning the molecular conformation. Several examples are demonstrated here: (1) nonequivalent C-H bonds present in alkenes and dienes. (2) different O-H and N-H stretching vibrations in alcohols and amines, (3) nonequivalent stretching frequencies of the axial equatorial C-H bonds inp-dioxane