The Iodine Spectrum: IodineSpectrum.mcd

The goal of this document is to present a systematic development of the relationship between spectroscopic experiments and the determination of molecular bond lengths in the excited state of diatomic molecules for which a high resolution vibronic spectrum is available. This document can serve as a template for students to use for data analysis of the UV-vis spectrum of I₂ or other diatomic gases. Use of this document as a template requires student UV-vis spectral data acquired in the laboratory. Faculty can also use this document with the enclosed sample data for student practice when an instrument is not available. The details of the Birge-Sponer plot are clearly illustrated. The document discusses the Morse potential and includes calculations with this potential function using correct units. Students can see clearly the mathematical steps leading to the calculation of the equilibrium bond length of the excited state of iodine. The Morse potentials for both the ground state and excited state permit discussion of the effect of excitation on molecular geometry. This document represents a way to make data analysis and work with the concepts for this experiment more efficient for students. Student exercises are fully integrated into the presentation and implementation of the mathematical concepts of this topic. References for the laboratory experiment are included.

Ground and excited electronic state Morse potentials from IodineSpectrum.mcd.