IR SPECTROSCOPY working& application.ppt

instrumentation, working and applications of IR spectroscopy

1. IR SPECTROSCOPY

2. SPECTROSCOPY SPECTROSCOPY IS THE STUDY OF INTERACTION BETWEEN ELECTROMAGNETIC RADIATION AND MATTER,THE MATTER CAN BE ATOMS MOLECULES OR IONS. Infrared radiation (IR),is a region of the electromagnetic radiation spectrum where wavelengths range from about 700 nanometers (nm) to 1 millimeter (mm).

3. IR SPECTROSCOPY Infrared (IR) spectroscopy is a technique used to study the interactions of molecules with infrared radiation. IT IS THE STUDY OF ABSORPTION OF IR RADIATION WHICH RESULT IN VIBRATIONAL TRANSITIONS . IR spectroscopy is widely used in chemistry, biochemistry, pharmaceuticals, materials science, and various other fields for qualitative and quantitative analysis of organic and inorganic compounds.

4. IR SPECTROSCOPY Mainly used in structural elucidation to determine the functional groups. IR region is present between visible and microwave region in EM spectrum. IR of EM spectrum is divided into 3 regions : Region Wave number Wavelength Near IR 14000-4000cm-¹ 0.8-2.5µm Middle IR 4000-400cm-¹ 2.5-25µm Far IR 400-10cm-¹ 25-1000µm

5. INSTRUMENTATION Infrared Source: Typically, the source emits infrared radiation across a wide range of frequencies. Sample Compartment: This is where the sample is placed for analysis. The sample can be in various forms such as liquids, solids, or gases. Monochromator: The monochromator selects a specific wavelength or frequency of infrared radiation for analysis. It helps to isolate the desired frequencies for accurate measurement.

6. INSTRUMENTATION Detector: The detector measures the intensity of the infrared radiation transmitted through or absorbed by the sample. Common detectors include thermocouples, photovoltaic cells, and bolometers. Data Processor: The data processor records and processes the output from the detector to generate the infrared spectrum of the sample. It may also perform data analysis and interpretation. Optics: Optics such as mirrors, lenses, and beam splitters are used to direct and focus the infrared radiation onto the sample and detector.

7. INSTRUMENTATION

8. Working principle The principle of IR spectroscopy is related to the vibrational and rotational energy of a molecule. When the frequency of the IR radiation is equal to the natural frequency of vibration, the molecule absorb IR radiation. Absorption of IR radiation causes an excitation of molecule from a lower to the higher vibrational level. Each vibrational level is associated with a number of closely placed rotational level. Therefore the IR spectroscopy is also called as "vibrational-rotational spectroscopy"

9. Working principle The IR spectroscopy theory utilizes the concept that molecules tend to absorb specific frequencies of light that are characteristic of the corresponding structure of the molecules. The energies are reliant on the shape of the molecular surfaces, the associated vibronic coupling, and the mass corresponding to the atoms. molecules absorb specific frequencies of infrared radiation that correspond to the vibrational modes of the chemical bonds within the molecule. When infrared radiation passes through a sample, some of the frequencies are absorbed while others are transmitted.

10. WORKING PRINCIPLE The IR spectrum is typically represented as a plot of absorbance or transmittance versus the frequency of infrared radiation. Different functional groups within the molecule absorb infrared radiation at characteristic frequencies, allowing for the identification of specific chemical bonds and functional groups within the molecule.

11. WORKING PRINCIPLE The change in the vibrational energy leads to another corresponding change in the dipole moment of the given molecule. The intensity of the absorption depends on the polarity of the bond. Symmetrical non-polar bonds in N≡N and O=O do not absorb radiation, as they cannot interact with an electric field.

12. Vibrations in ir spectroscopy Stretching Symmetric Asymmetric BENDING In-plane bending Scissoring Rocking Out-of-plane bending Wagging Twisting . ,

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14. SAMPLE The samples used in IR spectroscopy can be either in the solid, liquid, or gaseous state. Solid samples can be prepared by crushing the sample with a mulling agent which has an oily texture. A thin layer of this mull can now be applied on a salt plate to be measured. Liquid samples are generally kept between two salt plates and measured since the plates are transparent to IR light. Salt plates can be made up of sodium chloride calcium fluoride, or even potassium bromide. gaseous samples the sample cell must have a relatively long pathlength, i.e. light must travel for a relatively long distance in the sample cell.

15. APPLICATIONS Identification of Functional Groups: IR spectroscopy is widely used to identify functional groups in organic and inorganic compounds based on their characteristic absorption bands. Quality Control in Pharmaceuticals: IR spectroscopy is used to analyze the purity and composition of pharmaceuticals, ensuring product quality and consistency. Polymer Analysis: IR spectroscopy is used to characterize the structure and composition of polymers, including polymer additives and degradation products.

16. APPLICATIONS Environmental Analysis: IR spectroscopy is used for the analysis of environmental samples such as air pollutants, water contaminants, and soil components. Forensic Analysis: IR spectroscopy is used in forensic science for the analysis of trace evidence, including fibers, paints, and drugs. Food and Beverage Analysis: IR spectroscopy is used to analyze the composition, quality, and authenticity of food and beverage products.

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