Introduction to Infrared Spectroscopy

Infrared spectroscopy has proven to be a very informative and powerful technique for the characterization of zeolitic materials. Most infrared spectrometers measure the absorption of radiation in the mid-infrared region of the electromagnetic spectrum (4000-400 cm or 2.5-25 xm). In this region of the spectrum, absorption is due to various vibrational modes in the sample. Analysis of these vibrational absorption bands provides information about the chemical species present. This includes information about the structure of the zeolite as well as other functional 

Many excellent reviews on the application of infrared spectroscopy for characterization of silicoaluminates have been written and some are referenced here if a more thorough coverage of this topic is desired [81-89]. The purpose of this section is not to cover infrared spectroscopy of zeolites in great detail, but to give the reader an overview of the utility of the technique and the types of information that can be obtained. References are provided if more in-depth information is desired. 

We can visualize molecular vibrations by thinking of atoms and bonds as balls and springs. 

Zero-point energy is the term given to the energy of a molecule at absolute zero. 

Even at the absolute zero of temperature, atoms in a molecule vibrate with respect to the bonds that connect them. At room temperature, the molecules are distributed among various vibrational energy states. Frequency is a property of the vibration and is related to the difference between vibrational energy states by AE = hv (see Section 13.1). Promoting a molecule from a lower to a higher vibrational energy state increases the amplitude of the vibration. 

For a sense of the variety of vibrational modes available to a molecule, consider a CH2 group. Stretching and contracting the pair of C—H bonds can occur in two different ways. 

IP s earliest recognition came during World War II when it provided a key clue to the unusual p-lactam structure of the miracle drug penicillin. 

National Technical University of Athens, Chemical Engineering Department, Radiation Chemistry and Biospectroscopy, Zografou Campus, Zografou, Athens 

2 The three Infra red regions of interest in the electromagnetic spectrum 

In terms of wavelengths the three regions in micrometers (pm) are the following  

infrared spectroscopy is the study of the interaction of matter with hght radiation when waves travel through the medium (matter). The waves are electromagnetic in nature and interact with the polarity of the chemical bonds of the molecules [3]. If there is no 

The interaction of light and molecules forms the basis of IR spectroscopy. Here it will be given a short description of the Electromagnetic Radiation, the energy levels of a molecule and the way the Electromagnetic Radiation interacts with molecules and their structure [5,6]. 

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B.W. Cook, K. Jones. A Programmed Introduction to Infrared Spectroscopy. New York Heyden Son Inc, 1972. Excellent resource for the beginning spectroscopist. 

Briigel, W. An Introduction to Infrared Spectroscopy (translated from the German). Methuen, London, 1962. 

Using DEPT to Count Hydrogens Attached to C 570 2D NMR COSY and HETCOR 572 Introduction to Infrared Spectroscopy... 

W. Brugel, Introduction to Infrared Spectroscopy, Wiss. Forschungsber. Naiurw. Reihe 62, 1-366, 1954. A review, with 595 references, on the theory of infrared spectra, on apparatus and methods of study, and on the application to determination of molecular structure and chemical constitution, and to qualitative and quantitative analysis. 

An Introduction to Infrared Spectroscopy, W. Brugel, John Wiley Sons, Inc. (1962). A general introductory text. A discussion of American and West German instruments is included. 

Introduction to Infrared Spectroscopy 11 Table 1.1 Croup vibrations and their characteristic absorption wavenumber. 

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