COLLEGE OF SAINT MARY      PHYSICAL CHEMISTRY     FALL 2008

INSTRUCTOR: DR. PETER ILICH    YOUR NAME ___________________________

PROJECT # 2: INTERPRETATION OF INFRARED SPECTRA WITH THE HELP OF GAUSSIAN 03W PROGRAM

    The vibrational spectra of selected organic molecules (below) are measured by Fourier-Transform InfraRed, FTIR, spectrometer.  Two spectra are collected, a 4 cm-1 resolution spectrum, using a ZnSe ATR (Attenuated Total Reflectance) sample preparation technique, and a 1 cm-1 resolution spectrum, using BaF2 windows.  For each sample are collected 32 scans.

The following molecules have been selected:

    In the second stage of the project, Gaussian 03W program (in conjunction with the GaussView graphic interface program) is used to calculate the fundamental molecular vibrations in the harmonic approximations.  The Pople 6-311G basis set, enhanced by single diffuse function (+), 2d-polarization functions on the heavy atoms and p-polarization functions on hydrogens, is used within the hybrid, HF-DFT formalism, with the Becke 3-parrameter and Lee, Yang, Parr functional, B3LYP.

What to submit:

    Submit the annotated (labeled peaks) FTIR spectrum (the absorption mode), the list of G03W calculated harmonic frequencies and transition strengths, the G03W simulated IR spectrum.   Write a paragraph describing how you would assign the bands in the experimental IR spectrum , using the calculated vibrational modes, frequencies, and strengths.  Comment on the reliability of this type calculation in the interpretation of IR spectra.