Educational Applications of Infrared and Raman Spectroscopy: A Comparison of Experiment and Theory

Abstract

Advances in Raman spectroscopy and computer technology facilitate the introduction of current spectroscopic and molecular modeling methods at the undergraduate level. This study compares experimental infrared (IR) and Raman spectra of selected molecules to calculated spectra using semiempirical and ab initio methods. These illustrate the complimentary nature of IR and Raman spectroscopies as well as the limitation and successes of computational methods in predicting molecular vibrational frequencies and intensities. Particular examples used to illustrate these principles include comparisons of cis- and trans-1,2-dichloroethene as well as methanol and d1 -methanol. The former comparison illustrates symmetry selection rules, and the latter demonstrates the use of isotopic substitution in the assignment of vibrational spectra.

Raman Imaging Instrumentation

“…IR spectroscopy [84] and IR imaging [85,86] are methods commonly involving the study of the absorption properties of materials in the IR portion of the electromagnetic spectrum. The IR region of the electromagnetic spectrum may be broken down to the near-infrared (NIR) spectral region (0.8-1.4 mm), mid-infrared (MIR) spectral region (1.4-30 mm), and the far-infrared (FIR) spectral region (30-1000 mm).…”

Instrumental Proficiency Program for Undergraduates

“…The proficiency courses offer an opportunity for added depth of experience: to delve deeper into the theory, more hands-on experience, or introduction to extended techniques, for example, headspace GC, KBr pellets for IR, specular reflectance for IR, and so forth. 1 Currently six courses focusing on instrumentation typically encountered in the scientific workplace (not just chemistry) are available: (i) an Anasazi EFT-360 FTNMR (60 MHz), (ii) a Nicolet Avatar 360 FTIR, (iii) a Hewlett-Packard GCD GCMS, (iv) an Ocean Optics R2000 Raman, (v) an HPLC (components from several vendors controlled by PeakSimple software), and (vi) an Ocean Optics SP2000 UVvis coupled with a Buck Scientific VP-210 Flame AA. The courses are designed for self-directed study, relying on resources like the Analytical Chemistry by Open Learning (ACOL) series (5), selected computer-based training (CBT) programs (6) the Internet (the Analytical Sciences Digital Library Web site, ref 7, is an especially rich resource), and other textual resources to present the theoretical background.…”

“…Most of the experiments are "single purpose" in nature, focusing on analysis of a specific sample type or reaction or on one particular facet of the instrument's capability. A few experiments have focused on the comparison of instruments or techniques (e.g., 1,2 ) or the use of a single instrument in a broader perspective (e.g., 3,4 ).…”

High‐efficiency stimulated Raman scattering from alcohols: theory and experiments

“…development. 10 High-level electronic and vibrational structure calculation methods have found increasing use in optical properties studies. 11 Despite this evident success, there are still unanswered questions concerning the SRS efficiency of different kinds of materials and how the molecular structure must be changed in order to make better SRS materials.…”