Spectroscopy techniques, it's principle, types and applications

Spectroscopy and it's applications as well as it's types like Infrared spectroscopy and ultraviolet spectroscopy and principle of spectroscopy why we use spectroscopy.

1. Spectroscopy Presented by Nizad sultana

2. Spectroscopy Spectroscopy   is the study of the interaction between  matter and electromagnetic  radiation. Historically, spectroscopy originated through the study of  visible light  dispersed according to its  wavelength  by a  prism The electromagnetic spectrum is the range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies

3. Principle of spectroscopy The term " spectroscopy " defines a large number of techniques that use radiation to obtain information on the structure and properties of matter. The basic  principle  shared by all  spectroscopic  techniques is to shine a beam of electromagnetic radiation onto a sample, and observe how it responds to such a stimulus.

4. The history of spectroscopy began with  Isaac Newton 's optics experiments (1666–1672). Newton applied the word "spectrum" to describe the rainbow of colors that combine to form white light and that are revealed when the white light is passed through a prism. During the early 1800s,  Joseph von Fraunhofer  made experimental advances with dispersive spectrometers that enabled spectroscopy to become a more precise and quantitative scientific technique.

5. Why we use spectroscopy

6. Applications Spectroscopy is used as a tool for studying the structures of  atoms  and  molecules . The large number of wavelengths emitted by these systems makes it possible to investigate their structures in detail.

7. Spectroscopy also provides a precise  analytical method  for finding the  constituents  in material having unknown chemical  composition . In a typical spectroscopic analysis, a concentration of a few parts per million of a  trace element  in a material can be detected through its emission  spectrum

8. How to classify spectroscopy Spectroscopy can be defined by the type of radiative energy involved. The intensity and frequency of the radiation allow for a measurable spectrum. Electromagnetic radiation is a common radiation type and was the first used in spectroscopic studies. Both infrared (IR) and near IR use electromagnetic radiation, as well asmicrowave techniques.

9. Another way of classifying spectroscopy is by the nature of the interaction between the energy and the material. These interactions include absorption, emission .

10. IR Spectroscopy Range of electromagnetic spectrum that is used is Infrared radiation. Infrared is makeup of different radiations. Th e measurement of the interaction of  infrared radiation with matter by  absorption ,  reflection . Used to find functional group in molecules can liquid gaseous forms.

11. After absorbing energy molecules vibrate. Vibration of two typ Streching Symetrical Assymetrical Bending Scissoring Wagging Rocking Twisting

12. Bonds show different vibrations at different wavelengths. Different functional groups absorbs different wavelength of light so show different peaks.

13. Formula to find vibrations in linear molecules.

14. Spectrum Spectrum have two main regions. Absorbtion region:- Individual peaks we can identify easily. Fingerprinting region:- Multiple peaks We can’t identify easily But by matching with spectrum library. Represents bands of bending and stretching.

15. Applications To establish Identity of two compounds. To determine the structure of new compound from its functional group. To determine nature of contaiminants in a sample. Some advanced physical properties of material.

16. Vibrational energy depends upon following:- Mass of atom Strength of bonds and bond distance The arrangement of atom within molecule.

17. UV visible spectroscopy Why we need UV visible spectroscopy. We need to find concentration of different substances compounds mixtures. It can also tell us about chemical groups but data is not reliable. Also use in kinetic study in enzymatic activity. Also known as colour emmitery. Determining molar concenteration Determining ppm

18. Detector can be Photodiode PMT Photomultiplier Monochromator consists of 2 slits 1 prism First slit fall light to prism Second slit allow one wavelength of light to pass.

19. Cuvette with organic compounds or proteins. Proteins absorb wavelength if 260 NM. More protein more absorbtion. Less intensity of reflected light. I decrease. Transmitance ~ 1/absorbance Transmitance depends upon concentration of molecule.

20. Detector only detect transmitance than how we find absorbance. So we get graph.

21. To convert a value from percent transmittance (%T) to absorbance, use the following equation: Absorbance  = 2 – log(%T) Example:  convert  56%T to  absorbance : 2 – log(56) = 0.252  absorbance  units. Absorbance=10-1(concenteration× path length of cuvette) Concenteration less =transmitance more A=€ ×C×l

22. If we know absorbance than can calculate concenteration. C=A/€×l Because absorbance and concenteration does not have linear relationship. In order to know unknown sample we need a linear graph.

23. NMR Nuclear magnetic resonance We determine chemical and physical properties of different organic and inorganic molecules. Let say protein different atoms arrange in different ways. If we take example of hydrogen it consists of 1 proton and 1 electron. Proton is surrounded by electron. Proton spin it can behave as magnet. It is not just for Hydrogen also for other elements.

24. So this proton behave as magnet and it repel and try to rotate other atom present near it. NMR machine creates magnetic field. It directs this magnet in whatever direction it is to stable state.

25. How it is going to help us in determination of of structures. It tells us about special arrangement of atom with respect to each other. Cl -C-H2 HCl-C-H These are two different structures but IR can’t differencite between these two. But pattern of graph obtain help us to understand arrangements.

26. Cl H-C-H CH3 As Hydrogen arrange in electromagnetic field of NMR less energy is required to change its direction because it is shielded. But chlorine also present there it attracts all atoms of carbon towards it so more energy for Hydrogen alpha. For hydrogen beta less energy because chlorine electronegative effect is less.

27. Emission spectroscopy It uses to find how much concenteration of element present in sample. Or which element is present in sample sample we can use food products like noodles or cold drinks or something else. Atomic absorbtion Use to detect metallic elements that are present. Detect calcium magnesium potassium in serum. Lead in petrol.

28. Nabolizer :- Convert solid sample to aerosols. Flame role:- Dissolution :-evaporate the solvent Vapourization :-solute convert to gas Atomization :-dissociation produce atoms Excitation of atoms. Emission of atoms. Emission release different wavelength of light so unique spectrum obtained.

29. 1- Fluorescenece spectroscopy Fluorescence spectroscopy uses higher energy photons to excite a sample,which will then emit lower energy photos. This techniques has become popular for its biochemical and medical applications. Fluorescence spectroscopy is used in, among others, biochemical, medical, and chemical research fields for analyzing  organic compounds . There has also been a report of its use in differentiating malignant skin tumors from benign.

30. In the field of water research, fluorescence spectroscopy can be used to monitor water quality by detecting organic pollutants.  Recent advances in computer science and machine learning have even enabled detection of bacterial contaminaton of water.

31. 2- X-ray Spectroscopy: X-ray of sufficient frequencies interact with material and excite the atoms contained. Excitation radiations are absorbed or evolved if vice versa occurs. X-ray absorption and emission spectroscopy is used in chemistry and material sciences to determine elemental competition and chemical bonding. Very good and versatile techniques but a little complex. Overall X-ray diffraction techniques is one that is used most widely for bond length and angle measurements.

32. 7- Raman spectroscopy: Raman spectroscopy; is a spectroscopic technique typically used to determine vibrational modes of molecules, although rotational and other low-frequency modes of systems may also be observed. Raman spectroscopy is commonly used in chemistry to provide a structural fingerprint by which molecules can be identified. 

33. Spectrometer Spectrometer is apparatus to measure spectrum show intensity as function of Wavelength Frequency Energy Mass

34. Optical spectrometer Mass spectrometer Time of flight spectrometer

35. Optical spectrometer Show intensity of light as function of wavelength and frequency. The deflection is produced either by refraction in a prism or diffraction in a diffraction grating.

36. Mass spectrometer It is analytic instrument is analytical instruments that is used to:- Identify the amount and type of chemicals present in sample by measuring the mass to charge ratio abundance of gas phase ions.

37. Time of light spectrometer Determining the time of flight between two detectors If volocity is known masses can be determined.

38. Thank you all