Analysis of the Vibrational Spectrum of a Linear Molecule
Richard W. Schwenz
Department of Chemistry and Biochemistry, University of Northern Colorado, Greeley, CO 80639
William F. Polik
Department of Chemistry, Hope College, Holland, MI 49423
Sidney H. Young
Department of Chemistry, University of South Alabama, Mobile, AL 36688
Translated to Mathematica by:
Laura Yindra
Department of Chemistry, University of Wisconsin—Madison, Madison, WI 53715
Abstract
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More Information: Keywords, JCE Citation
Abstract
This document provides a moderately interactive tutorial describing the analysis of vibrational frequencies obtained from the infrared spectrum of hydrogen chloride. The hcl.txt file contains sample data that was created using a standard spreadsheet program. The Mathcad document treats the data by using nonlinear curve-fitting to obtain the spectroscopic parameters. Students are directed to another document to learn more details of the nonlinear curve-fitting procedure. For the typical student in a first course in physical chemistry the material contained here is sufficient. The importance of the approach presented here is that students are easily able to obtain the molecular constants and their standard deviations in a single regression step using multiple regression. The document contains questions for students to answer as they analyze the sample spectrum. After practicing with the sample data, students may use the worksheet to complete very quickly an analysis of the data they collected in the physical chemistry laboratory. Throughout the worksheet students are challenged to think and reflect on the concepts associated with rotational-vibrational spectroscopy rather than being consumed by the details of the data analysis. Practice with the test data gives students an efficient way of learning the computational details. This maximizes their productivity as learners. The document contains mastery exercises to challenge students and test their understanding of the material.
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Interactive Versions (fully interactive with program version listed)
 See also the following data file: hcl.txt
Non-interactive versions (PDF)
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JCE Subscribers only: Institutional IP number access or name and password required
Commentary
 Editor's Commentary
Other Information
Keywords
Domain: Laboratory Instruction; Physical Chemistry; Physical Chemistry; Pedagogy: Computer-Based Learning; Topics: Chemometrics; IR Spectroscopy; IR Spectroscopy; Mathematics / Symbolic Mathematics; Molecular Properties / Structure; Quantum Chemistry;
JCE Citation
Schwenz, R. W.; Polik, W. F.; Young, S. H. J. Chem. Educ. 2000 77 670.
Yindra, L. R. J. Chem. Educ. 2004, 81, 606. |
