IUPUC faculty member Guillermo Garcia, Ph.D., recently presented at an IUPUI Department of Physics Colloquium.

Garcia’s presentation was entitled, “An Investigation Into the Limitations of the Harmonic Approximation to Predict Vibrational Isotopic Shifts.”

Based on his research, Garcia spoke about a method for the identification of new molecular species. For molecules with near-lying vibrational fundamentals, experimental and theoretical factors complicate the interpretation of isotopic spectra where isotopic shift measurements are recorded. Experimentally, a large number of absorptions in a small region of the spectrum are observed. Theoretically, two factors affect the calculation of isotopic shifts in the harmonic approximation: i) the sensitivity of the calculations due to the interaction of vibrational fundamentals and ii) the sensitivity of the calculations due to the anharmonicity of the interaction potential.

To aid in his study, Garcia developed two theoretical methods in the framework of perturbation theory as a consequence of investigating the issues that affect the calculations. Garcia discussed his techniques and their applications to the isotopic spectra of carbon chains.

Garcia is a lecturer of physics for the IUPUC Division of Science.