Interpretation of Infrared and Raman Spectra
Bowdoin College, Brunswick, Maine – July 11-15, 2022
Infrared spectroscopy is the most popular and cost effective technique for the structural elucidation of relatively simple organic molecules as well as many polymers. While comparison of the spectrum of an unknown sample with spectral libraries may sometimes identify the material correctly, this is not always the case. For example, the sample may often be a mixture or the authentic reference spectrum of the material is not contained in the available libraries. Even then the infrared spectrum of a material gives important information about the molecular structure of the compounds that are present in the sample. The ability to interpret infrared and Raman spectra and hence to identify the presence or absence of organic functional groups and their surrounding environment is vital to anyone using an infrared spectrometer. It is this need that this course addresses. Raman spectroscopy is an important complement to infrared spectroscopy, particularly with the advent of hand-held Raman spectrometers. Where appropriate, it will be shown how Raman spectra give structural information not readily accessible from the infrared.
Following an introductory discussion of the theory of infrared and Raman spectroscopy, a set of four lectures focuses on spectral data associated with the hydrocarbon platform supporting the various functional groups. Next follows a set of three lectures centered on a variety of functional groups including OH, NH, C-O, C-N and other polar groups. Special emphasis is placed on C=O systems because the infrared spectrum is particularly sensitive to the molecular structure supporting the frequently encountered carbonyl group.
The complete set of lectures is designed to introduce the participant to the strategies involved in the efficient interpretation of the spectrum of an unknown compound. Coupled to the lecture program is a set of exercises that has proven particularly successful in the development of the necessary skills to handle routine investigations. A separate lecture concerns purely inorganic materials. The week includes two lectures that cover a variety of standard sample handling procedures. One of these lectures is devoted to methods that deal with samples that contain mixtures of materials.
In this course, no previous experience with infrared theory or technology is required, but some background in organic chemistry and its associated terminology is assumed and is essential.
The staff will be available during the week to consult on individual problems of interest to the participants.
In general, lectures will be presented from 8:30 a.m. to noon. On Monday only there will be an afternoon lecture session. In the evening is the course banquet, a Maine Lobster Bake. On Tuesday, Wednesday and Thursday afternoons or evenings, small participant groups will be organized for workshop sessions for the interpretation of infrared and Raman spectra.
During the afternoon or evening workshops, a total of about 50 representative infrared and Raman spectra will be assigned as unknowns to be identified or utilized in other appropriate problems. Standard reference catalogs of spectra, as well as computerized databases, will be available for use by the participants to evaluate their solutions to these problems. All the lecture staff will be available for advice and consultation during these workshops.
Updated November 21, 2021.