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Tuesday, February 28, 2012

PowerPoint Presentation On Principles of Spectroscopy UV and IR

PPT On Principles of Spectroscopy UV and IR


Presentation Transcript:
1. Identification of Compounds

I. Introduction of Spectrometric Analyses
II. Ultra Violet Spectrometry
III. Infrared Spectrometry
IV. Nuclear Magnetic Resonance Spectrometry
V. Mass Spectrometry

3. I. Introduction of Spectrometric Analyses
The study how the sample interacts with different wavelength in a given region of electromagnetic radiation is called spectroscopy or spectrochemical analysis.

The collection of measurements signals (absorbance) as a function of electromagnetic radiation is called a spectrum.

4. Energy Absorption
The mechanism of absorption energy is different in the Ultraviolet, Infrared, and Nuclear Magnetic Resonance regions. However, the fundamental process is the absorption of certain amount of energy.

The energy required for the transition from a state of lower energy to a state of higher energy is directly related to the frequency of electromagnetic radiation that causes the transition.

5. Quantum Numbers and Orbitals
Principal quantum number (n): The average distance of the electron from the nucleus. 1, 2, and so on.

Azimuthal quantum number (Momentum quantum number) (l): The shape of the orbital. 1s, 2s, 2p, 3s, 3p, 3d, etc

Magnetic quantum number (Orientational quantum number) (ml): The orientation of orbital in the space. 2px 2py, 2pz x, y and z are orientational quantum number

Electron spin quantum number (ms)= The two possible orientation of the electron in a magnetic field. 1/2 or –1/2

6. II. Ultra Violet Spectrometry
The absorption of ultraviolet radiation by molecules is dependent upon the electronic structure of the molecule. So the ultraviolet spectrum is called electronic spectrum.

7. Electronic Excitation
The absorption of light energy by organic compounds in the visible and ultraviolet region involves the promotion of electrons in , , and n-orbitals from the ground state to higher energy states . This is also called Energy Transition. These higher energy states are molecular orbitals called antibonding.

8. Electronic Molecular Energy Levels
The higher energy transitions ( *) occur a shorter wavelength and the low energy transitions (*, n *) occur at longer wavelength.

9. III. Infrared Spectrometry
Radiation energy in the infrared region is absorbed by the organic compound and converted into energy of molecular vibration.

The energy absorption pattern thus obtained is commonly referred to as an infrared spectrum which has the plot of intensity of radiation absorption versus wavelength of absorption.

10. Thanks.
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