Chapter 6 - Chapter 6 An Introduction to Spectrometric...

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Chapter 6 An Introduction to Spectrometric Methods Spectrometric methods are a large group of analytical methods that are based on atomic and molecular spectroscopy. Spectroscopy deals with the interactions of various types of radiation (mainly electromagnetic radiation) with matter. Spectrometry and spectrometric methods refer to the measurement of the intensity of radiation with a photoelectric transducer or other types of electronic device.
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Electromagnetic Radiation Electromagnetic Radiation: Kind of energy with wave character that can be characterized by using wavelength ( λ ), frequency ( ν ), velocity and amplitude. Electromagnetic radiation requires no supporting medium for its transmission and passes readily through a vacuum. Electromagnetic radiation is a stream of discrete particles or wave packets of energy called photons where energy is proportional to the frequency of the radiation.
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Wave Parameters Amplitude (A): Length of the electric vector at a maximum in the wave. Period (P): The time in seconds required for the passage successive maxima or minima through a fixed point in space. Frequency ( ν ): The number of oscillations of the field that occur per second and is equal to 1/ P. (s -1 or Hz). Wavelength ( λ ): The linear distance between any two equivalent points on successive waves (successive maxima or minima). (A, nm, etc.).
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Velocity of propagation: V i = ν x λ i In vacuum, the velocity of radiation is independent of wavelength and given by the symbol c. c = νλ = 3.00 x 10 8 m/s = 3.00 x 10 10 cm/s Wavenumber ( ν ): The reciprocal of the wavelength in centimeters (cm -1 ). The Electromagnetic Spectrum: The electromagnetic spectrum encompasses an enormous range of wavelength and frequencies. Spectroscopic methods are classified according to the wavelengths or frequencies that are important for analytical purpose.
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Planck’s Equation: The relationship between frequency ν of light and energy E, E = h ν ; where, h = Planck’s constant = 6.6 x 10 -27 erg.sec = 6.6 x 10 -34 joule.sec In vacuum, velocity of light = c = νλ = 3 x 10 10 cm/s which gives, ν = c/ λ E = h(c/ λ ) = hc ν (where, ν = 1/ λ = wavenumber) Energy directly proportional to wavenumber
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Interactions of Electromagnetic Radiation Physical Interactions:
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Chapter 6 - Chapter 6 An Introduction to Spectrometric...

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