Tunable lasers are used to study the visible spectra of vibrational overtones (Delta v=5,6,7,etc.) in molecules with X-H bonds (X=C,N,O,S, etc.). These high overtones absorb only weakly, and the powerful light of the laser is needed for the studies. The overtone energies are sensitive to the local environment, with electronic interactions causing measurable shifts in absorption energies. The effects of molecular conformation on the overtone energies are also observed. This sensitivity to the local environment allows overtone spectroscopy to probe directly the bond strength, thus providing a link between molecular structure and chemical reactivity.
 

Publications
C-H strectching overtone spectrum of propylene. Molecular orbital analysis is the local mode model, R. L. Swofford, H. L. Fang, McDevitt and Anderson, J. Phys. Chem., 1985, 89, 225.

 Theoretical description of the overtone spectra of acetaldehyde using the local mode approach., R. L. Swofford, H. L. Fang, Findsen and Birge, J. Chem. Phys., 1986, 84, 16.

 A surface laser-light scattering spectrometer with adjustable resolution. R. L. Swofford, R. B. , Dorshow and A. Hajiloo, J. Appl. Phys. 1988, 63, 1265.

 Surface laser-light scattering, R. L. Swofford and R. B. Dorshow. Phys. Today, 1988, 41[1] S-49.

 Application of surface laser-light scattering spectroscopy to the photoabsorbing systems: The measurement of interfacial tension and viscosity in crude oil. R. B. Dorshow and R. L. Swofford, J.Appl. Phys. 1989, 65, 3756.

 An adjustable-resolution surface laser-light scattering spectrometer and it application to the measurement of interfacial tension and viscosity in crude oil system. R. B. Dorshow and R. L. Swofford, Colloids and Surfaces 1990, 43, 133.

 Inclusion Complexes of N-Benzoyl-D-leucine and N-Benzoyl-L-leucine with Beta-Cyclodextrin by Raman Spectroscopy, R. Spivey and R. L. Swofford, Appl. Spectrosc. 53, 435 (1999).

 Experimental and ab initio investigation of the O–H overtone vibration in ethanol, J. D. Weibel, C. F. Jackels, and R. L. Swofford, J. Chem. Phys. 117, xxxx (2002). (published September 1, 2002)