**1. Introduction**

48 Advanced Aspects of Spectroscopy

New York,(2000).

York (1962).

(1967).

(1964).

Springer New York (2011).

[6] Journal of "Coordination Chemistry Reviews". [7] Journal of Spectrochimica Acta A Elsvier.

[9] Journal of Solid State Communications.

[1] B.N.Figgs,M.A.Hitchman, "Ligand Field Theory and Its Applications",Wiley-VCH,

[2] A.Lund, M.Shiotani, S.Shimada,"Principles and Applications of ESR Spectroscopy",

[3] C.J.Ballahausen, "Introduction to Ligand Field Theory", Mc Graw-Hill Book Co., New

[4] P.B. Ayscough,"Electron Spin Resonance in Chemistry", Mathuen & Co., Ltd., London

[8] J.S.Griffith, "Theory of Transition Metal Ions", Cambridge University Press,Oxford

[5] R.L.Carlin, "Transition Metal Chemistry", Marcel Dekker,New York (1969).

**21. References** 

FTIR Spectroscopy is a technique based on the determination of the interaction between an IR radiation and a sample that can be solid, liquid or gaseous. It measures the frequencies at which the sample absorbs, and also the intensities of these absorptions. The frequencies are helpful for the identification of the sample's chemical make-up due to the fact that chemical functional groups are responsible for the absorption of radiation at different frequencies. The concentration of component can be determined based on the intensity of the absorption. The spectrum is a two-dimensional plot in which the axes are represented by intensity and frequency of sample absorption.

The infrared region of the electromagnetic spectrum extends from the visible to the microwave (Figure 1).

**Figure 1.** Schematic representation of the electromagnetic spectrum (adapted from http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/Spectrpy/UV-Vis/spectrum)?

© 2012 Simonescu, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Infrared radiation is divided into:


Because all compounds show characteristic absorption/emission in the IR spectral region and based on this property they can be analyzed both quantitatively and qualitatively using FT-IR spectroscopy.

Today FT-IR instruments are digitalized and are faster and more sensitive than the older ones. FT-IR spectrometers can detect over a hundred volatile organic compounds (VOC) emitted from industrial and biogenic sources. Gas concentrations in stratosphere and troposphere were determined using FT-IR spectrometers (Puckrin *et al*., 1996).

In case of environmental studies FTIR Spectroscopy is used to analyze relevant amount of compositional and structural information concerning environmental samples (Grube *et al.,* 2008). The analysis can be performed also to determine the nature of pollutants, but also to determine the bonding mechanism in case of pollutants removal by sorption processes. Techniques for measuring gas pollutants such as continuous air pollutants analyzer (SO2, NO2, O3, NH3), on-line gas chromatography (GC) used simple real-time instruments to quantify gas pollutants. They need to use several sensors in order to analyze multiple gas pollutants simultaneously.

FT-IR spectroscopy coupled with other spectroscopic techniques such as AAS (atomic absorption spectroscopy) have been used to assess the impact of industrial and natural activities on air quality (Kumar *et al*., 2005; Childers *et al*., 2001).

In addition to the traditional transmission FTIR (T-FTIR) methods (e.g. KBr-pellet or mull techniques), modern reflectance techniques are widely used today in environmental, agricultural, pharmaceuticals, and food studies. These modern techniques are attenuated total reflection FTIR (ATR-FTIR), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The choice of the method to be used depends on many factors such as: the information needed (bulk versus surface analysis), the physical form of the sample, the time required for sample preparation (Majedová *et al*., 2003).

In the following there will be presented some of the most important research studies related to the involvement of FTIR spectroscopy in environmental studies.
