Question

How does a Fourier Transform Infrared Spectrometer (FTIR) work? Summarize the method and give figures and curves to explain the description.

Give at least 3 references.

Answer 1

Fourrier Transform Infrared Spectroscopy.( FTIR)

It will give the idea about the vibrational structure of the moleclue.
ie., you can get an idea about the frequencies, vibrational modes in a perticular molecule

The idea of IR is that certain bonds will absorb infrared radiation and vibrate. When they do, the IR Radiation is absorbed and it does not reach the detector. At that frequency, an absorbance is recorded on a spectrum.

An FTIR uses a computer to run multiple IR analyses one after another. The IR analyses are combined into a single result, which helps eliminate the affect of trial-by-trial randomness of absorbance.

Fourier Transform Infrared Spectoscopy is a technique used to obtain an infraed spectrum of absorption or emission of a gas, liquid or solid, which collects high spectral resolution data over a spectral range that confers measures intensity over a narrow range of wavelengths at a time. IN EASIER WORDS you can obtain the absorption or emission of sample matter by infrared spectoscopy, and the machine will give you a convertion of the values using Fourier Transform as a mathematic method for the interferogram obtain by the superposition of both beam light. The fundament of the method is the Michelson interferometer that is generated by making measurements of the signal at many discrete positions of the moving mirror.

Some of the major applications of IR spectroscopy are as follows:

1. Identification of functional group and structure elucidation

Entire IR region is divided into group frequency region and fingerprint region. Range of group frequency is 4000-1500 cm-1 while that of finger print region is 1500-400 cm-1.

In group frequency region, the peaks corresponding to different functional groups can be observed. According to corresponding peaks, functional group can be determined.

Each atom of the molecule is connected by bond and each bond requires different IR region so characteristic peaks are observed. This region of IR spectrum is called as finger print region of the molecule. It can be determined by characteristic peaks.

2 Identification of substances

IR spectroscopy is used to establish whether a given sample of an organic substance is identical with another or not. This is because large number of absorption bands is observed in the IR spectra of organic molecules and the probability that any two compounds will produce identical spectra is almost zero. So if two compounds have identical IR spectra then both of them must be samples of the same substances.

3 Studying the progress of the reaction

Progress of chemical reaction can be determined by examining the small portion of the reaction mixure withdrawn from time to time. The rate of disappearance of a characteristic absorption band of the reactant group and/or the rate of appearance of the characteristic absorption band of the product group due to formation of product is observed.

4. Detection of impurities

IR spectrum of the test sample to be determined is compared with the standard compound. If any additional peaks are observed in the IR spectrum, then it is due to impurities present in the compound.

5. Quantitative analysis

The quantity of the substance can be determined either in pure form or as a mixure of two or more compounds. In this, characteristic peak corresponding to the drug substance is chosen and log I0/It of peaks for standard and test sample is compared. This is called base line technique to determine the quantity of the substance.