Infrared spectroscopy,basic principle,application ,graphs and application
- 2. INTRODUCTION Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the interaction of infrared radiation with matter . It covers a range of techniques, mostly based on absorption spectroscopy. As with all spectroscopic techniques, it can be used to identify and study chemical substances. Samples may be solid, liquid, or gas. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer to produce an infrared spectrum. An IR spectrum can be visualized in a graph of infrared light absorbance on the vertical axis vs. frequency or wavelength on the horizontal axis.
- 3. Principle Of Infrared Spectroscopy 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. For instance, the molecule can absorb the energy contained in the incident light and the result is a faster rotation or a more pronounced vibration.
- 4. INSTRUMENTATION In infrared spectra the absorption peaks point downward because the vertical axis is the percentage transmittance of the radiation through the sample. Absorption of radiation lowers the percentage transmittance value. Since all bonds in an organic molecule interact with infrared radiation, IR spectra provide a considerable amount of structural data. There are four types of instruments for infrared absorption measurements available: -Dispersive grating spectrophotometers for qualitative measurements -Nondispersive photometers for quantitative determination of organic species in the atmosphere -Reflectance photometers for analysis of solids -Fourier transform infrared (FT-IR) instruments for both qualitative and quantitative measurements.
- 6. Infrared light sources The Nernst glower The globar source The carbon dioxide laser Detectors Bolometer Sample holder INSTRUMENTS IN INFRARED SPECTROMETER
- 8. APPLICATIONS To compare spectrum. No two sample will have identical IR spectrum. Used for determination of molecular structure. To study the progress of reaction. Detection of impurities. Study isomerism in organic chemistry. Identify the shape of symmetry of molecule
- 9. THANKYO U