Ftir Introduction (irene)

Introduction Fourier transform infrared spectroscopy (FTIR) is a measuring technique of getting the infrared spectra by measuring the interferogram (time-domain signal) of the samples with the use of interferometer and then the interferogram is Fourier transformed to give the spectrum (frequencydomain functions). Fourier transform is a data processing tool and infrared spectroscopy is the study of interaction of infrared radiation with matter with the resultant spectrum showing the absorption due to various distinctive functional groups, giving a molecular fingerprint of the studied compound. FTIR can be applied for the identification of the unknown, determination of the quality of the sample and the components of a mixture. There are mainly two common types of infrared sampling techniques-they are the transmission techniques and the reflectance techniques. For the transmission mode, the infrared radiation beam passes through the sample directly. And it is the most popular way of obtaining the infrared spectra because of its various advantages such as it is relatively inexpensive, having high signal to noise ratio and universal –can work on various kinds of samples such as polymers, gases, liquids and solids that can be ground into a powder with alkaline metal halide such as KBr pellet or suspended in an oil. In the reflectance technique, the infrared light beam is bounced off the sample rather than passing through the sample. The reflectance technique can solve the thickness problem that the transmission mode may have. Hence, the method is less time consuming as there is no need for the sample to be in the proper concentration, thickness or the proper amount of light passing through and hence no dilution or grinding of the sample is required. And the method is non-destructive. Hence, the technique can be applied to case where it is difficult to study with the transmission technique. The attenuated total reflection (ATR) and the Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) are studied in this experiment. DRIFTS can be used to examine powder and solid, even very large and intractable samples such

as pieces of plastic and furniture. ATR can be applied to examine polymer films and semisolid samples such as shampoo, toothpaste and tomato sauce etc. In this experiment, various milk and polymer samples are studied with the reflectance measurement techniques using the FTIR spectrophotometer.