UV SPECTROSCOPY.pptxasdasdasdasdsdsaasads

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1. UV SPECTROSCOPY SPECTROSCOPY :- DEFINITION:- Spectroscopy is that branch of science which deals with the study of interaction of electromagnetic radiation with matter.

2. INTERACTION OF ELECTROMAGNETIC WAVE AND MATTER

3. INTRODUCTION UV spectroscopy is the type of absorption spectroscopy in which light of the ultra-violet region(200-400nm) is absorbed by the molecule which results in the excitation of the electrons from the ground state to a higher energy state. The alternate title for this technology is a ‘ELECTRONIC SPECTROSCOPY’.

4. UV Spectroscopy (Ultraviolet Spectroscopy) is a technique in physics and chemistry used to study the absorption of ultraviolet (UV) light by a substance, typically in the wavelength range of 10 nm to 400 nm. This interaction provides information about the electronic structure of molecules, as UV light has enough energy to excite electrons from lower energy levels to higher energy levels.

5. PRINCIPLE OF UV SPECTROSCOPHY The principle of UV SPECTROSCOPHY is based on the absorption of ultraviolet (UV) light by molecules, leading to electronic transitions within the molecule. These transitions occur as electrons in the molecule absorb energy from the UV light and move from a lower energy state (ground state) to a higher energy state (excited state). Here's a detailed breakdown of the principle:

6. 1.Absorption of UV Light: When UV light passes through a substance, some of it may be absorbed by the molecules of that substance. The absorption occurs because the energy from the UV light is used to excite electrons from their ground state (lower energy level) to an excited state (higher energy level). 2. Electronic Transitions: The UV region of the electromagnetic spectrum has enough energy to promote transitions between molecular orbitals , specifically: σ → σ * transitions: Involves electrons in single bonds (σ-bonds) like C-C bonds, but requires very high-energy UV light. π → π * transitions: Common in compounds with double bonds (π-bonds), such as alkenes or aromatic rings. n → π * transitions: Involves non-bonding electrons (lone pairs) in functional groups like carbonyls (C=O).

7. 3.Beer-Lambert Law: The absorption of light by a substance follows the Beer-Lambert Law , which relates the absorbance (A) to the concentration (c) of the absorbing species, the path length (l) of the sample, and the molar absorptivity (ε) of the substance: A= ε lc A is the absorbance (how much light is absorbed), ε is the molar absorptivity (a constant that depends on the substance and the wavelength of light), l is the path length through the sample (usually in cm), c is the concentration of the absorbing species in the sample . 4. Absorption Spectrum: The absorption of UV light by a substance is measured over a range of wavelengths, producing an absorption spectrum . This spectrum displays peaks where absorption occurs, corresponding to the wavelengths where electronic transitions take place. The peak wavelength ( λmax ) gives information about the types of bonds or functional groups present in the molecule. The intensity of the peak is related to the concentration of the substance and the nature of the electronic transition.

8. 4. Absorption Spectrum: The absorption of UV light by a substance is measured over a range of wavelengths, producing an absorption spectrum . This spectrum displays peaks where absorption occurs, corresponding to the wavelengths where electronic transitions take place. The peak wavelength ( λmax ) gives information about the types of bonds or functional groups present in the molecule. The intensity of the peak is related to the concentration of the substance and the nature of the electronic transition.

9. INSTRUMENTATION Single Beam UV Spectrophotometer Double Beam UV Spectrophotometer

10. Main Components of a UV Spectrophotometer : Light Source(Radiation source) : Deuterium Lamp : For UV light (typically 160–375 nm), this lamp produces a continuous spectrum in the UV range. Tungsten-Halogen Lamp : For the visible region (typically 375–700 nm) Collimating lens. prism/gratings. Exit slit. Sampling:- transparent, free from any particles, Sample Holder ( Cuvette ):- Quartz & sometimes glass. Detector :- photomultiplier tubes(PMT), photodiode array & diode array detectors(PDA), Charged couple device(CCD). Processor/Readout

11. UV SPECTRUM

12. APPLICATION UV spectroscopy is used in various fields, such as: Chemical Analysis: Identifying functional groups and determining molecular structure. Concentration Measurements: Quantifying the concentration of a substance in a solution. Pharmaceuticals : Monitoring drug purity and concentration. Biochemistry : Studying proteins, nucleic acids, and other bio molecule.