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SPECTROSCOPIC METHODS OF ANALYSIS

SPECTROSCOPIC METHODS OF ANALYSIS. INTRODUCTION TO SPECTROSCOPY. SPECTROSCOPY. T he study of the interaction between matter and radiated energy.

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SPECTROSCOPIC METHODS OF ANALYSIS

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  1. SPECTROSCOPIC METHODS OF ANALYSIS INTRODUCTION TO SPECTROSCOPY

  2. SPECTROSCOPY The study of the interaction between matter and radiated energy. Originated through the study of visible light dispersed according to its wavelength. Later the concept was expanded greatly to comprise any interaction with radiative energy as a function of its wavelength or frequency. Representation of Spectroscopic Data (Spectrum) • Plot of the response of interest vs. wavelength, frequency or energy.

  3. SUMMARY Spectroscopyand spectrography are terms used to refer to the measurement of radiation intensity as a function of wavelength and are often used to describe experimental spectroscopic methods.

  4. ELECTROMAGNETIC RADIATION (EMR) May be described in terms of a stream of photons, each travelling in a wave-like pattern and moving at the speed of light. Photons: massless particles Each photon contains a certain amount (or bundle) of energy, and all electromagnetic radiation consists of these photons.

  5. Emr EM waves are typically described by any three of the following physical properties: the frequency, the wavelength, and photon energy. • Frequency (v)/(f): The number of cycles the wave undergoes in one second. Measured in Hz or s-1. • Wavelength (λ): The distance between any point on a wave and the corresponding point on the next crest or trough. Measured in nanometers (10-9m)/picometers (10-12m)/angstrom (A°)(10-10m). • Speed: Distance per unit time.

  6. Emr

  7. Emr Frequencies range from about a million billion Hertz (gamma rays) down to a few Hertz (radio waves). • Wavelength is inversely proportional to the wave frequency, so gamma rays have very short wavelengths that are fractions of the size of atoms, whereas radio wavelengths can be as long as a several thousand kilometers. • Photon energy is directly proportional to the wave frequency, so gamma rays have the highest energy and radio waves have very low energy.

  8. Emr These relations are illustrated by the following equation E = hvand its variations below:- Where: • c = 3 x 108  m s-1 (speed of light in vacuum) • h = 6.626 ×10−34 Js-1 (Planck's constant).

  9. QUESTION A mother uses a microwave oven to heat a meal for her children. The wavelength of the radiation is 1.2cm. What is the energy of 1 photon of this microwave oven?

  10. QUESTION = = 2.5 x 1010s-1 E = hV = (6.626 x 10-34Js-1) x (2.5 x 1010s-1) E = 1.657 x 10-23 J

  11. THE EM SPECTRUM The types of electromagnetic radiation are broadly classified into the following classes: • Gamma radiation • X-ray radiation • Ultraviolet radiation • Visible radiation • Infrared radiation • Microwave radiation • Radio waves

  12. THE EM SPECTRUM

  13. THE EM SPECTRUM

  14. INDEPENDENT STUDY Research the relative energies and dangers associated with exposure to high energy wavelengths.

  15. SPECTROSCOPY IN CHEMICAL ANALYSIS

  16. SPECTROSCOPY IN CHEMICAL ANALYSIS

  17. Atoms absorb photons of certain or fixed wavelengths or fixed quantum of energy and become excited from lower to higher energy states. Spectroscopy is the study of how light or photons or electromagnetic radiation reacts with matter. It is a useful analytical tool. An advantage to spectroscopy is that little or no damage is caused to the sample except in mass spectroscopy.

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