Infrared instrumentation

INFRARED INSTRUMENTATION

1. PRESENTATION ON INSTRUMENTATION OF INFRAFRED SPECTROSCOPY PRESENTED BY :- SAURABH VERMA M.S. PHARM ,NIPER ,KOLKATA

2. Infrared (IR) Spectroscopy

3. INFRARED REGION X-RAY ULTRAVIOLET INFRARED MICRO- WAVE RADIO FREQUENCY Ultraviolet Visible Vibrational Infrared (Mid-IR) Nuclear magnetic resonance 200 nm 400 nm 800 nm 2.5 m m 25 m m 1 m 5 m BLUE RED 0.78-1000 ɥM

4. ORGANIC STRUCTURE DETERMINATION

5. SOURCE SAMPLE MONOCHROMATOR DETECTOR READOUT Nernst Glower Globar Incandescent wire source Hg Arc Grating Filter Thermal D Thermocouple Thermopile Thermister Bolometer Pyroelectric D Recorder INSTRUMENTATION

6. 1. IR radiation source

7. 1. The Nernst Glower

8. 2. The Globar source

9. 4. The Mercury Arc.

10. 3. Incandescent Wire Source

11. 2. MONOCHROMATORS Prism:- Used as dispersive element. Constructed of various metal halide salts Sodium chloride is most commonly prism salt used. These salts are subjected to mechanical & thermal instability or water solubility. Protection against damage must be continuously exercised.

12. B. Grating Gratings are nothing but rulings made on some materials like glass, quartz or alkylhalides depending upon the instrument, The mechanism is that diffraction produces reinforcement. The rays which are incident upon the gratings gets reinforced with the reflected rays.

13. Advantages over Prism:-

14. 3. Sample cell & Sampling of substance Infrared spectra may be obtained for gases, liquids or solids (neat or in solution) Material containing sample must be transparent to the IR radiation . So, the salts like NaCl , KB r are only used.

15. A. Sampling of solids Various techniques used for preparing solid samples are as follows:- Solid run in Solution – In this technique, solid sample may be dissolved in a non-aqueous solvent. Provided that there is no chemical interaction with the solvent and the solvent is not absorbed in the range to be studied. A drop of solution is placed on the surface of alkali metal disc solvent is to dryness leaving a thin film of the solute.

16. 2. Solid film technique If the solid is amorphous in nature. Then the sample is deposited on the surface of a KBr or NaCl cell by evaporation of a solution of the solid. Ensured that the film is not too thick to pass the radiation

17. 3. Pressed pellet technique In this technique, a small amount of finely ground solid sample is mixed with 100 times its weight of potassium bromide and compressed. To form thin transparent pellet (1-2mm thick & 1cm in diameter) using a hydraulic press. These pellets are transparent to IR radiation and it is used for analysis .

18. Advantages:- Kbr pellets stored for long period of time . Resolution of spectrum is superior . Disadvantages:- Always have a band at 3450cm -1 due to OH group of moisture. Due to high pressure(~25000 psig ) polymorphic changes occurs. Not successful for polymers. ( diffcult to grind with Kbr .)

19. 4. Mull technique

20. 2. Sampling of liquids

21. 3. Sampling of gases

22. DETECTORS The detectors can be classified into three categories: Thermal detectors:- Their responses depend upon the heating effect of radiation . P yroelectric detectors :- P yroelectric effect depends on the rate of change of the detector temperature rather than on the temperature itself. Photoconducting detectors:- Most sensitive .

23. Thermocouples Metal A Metal B welded junction (cold) welded junction (hot)

24. To enhance sensitivity several thermocouples connected in series are called a “thermopile”

25. Bolometer

26. THERMISTORS

27. THANK YOU.