Lecture 5 - Lecture 5 Chapter 18: Spectroscopy (Light-...

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Anal Chem 251 Lect 5 Spectroscopy 1 Lecture 5 Chapter 18: Spectroscopy (Light- Electromagnetic Spectrum) (Corresponding Exp – Phosphate Analysis) Reviewing Light from Freshman Chem slides 3 - 14 Derviation of Beer’s Law slides 38 - 44 Turbidimetry (Corresponding Exp – Sulfate Analysis)
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Anal Chem 251 Lect 5 Spectroscopy 2 Spectroscopy, Spectrometry, Spectrophotometry - Definition Spectroscopy : The interaction of radiation and matter are the subject of the science called spectroscopy. Spectroscopic analytical methods are based on measuring the amount he amount of radiation produced or absorbed by molecular or atomic species of rest. Spectrochemical methods are used for: methods are used for: of molecular structure ative determination of inorganic and organic
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Anal Chem 251 Lect 5 Spectroscopy 3 Figure 7.1 Frequency and Wavelength c = λ ν The Wave Nature The Wave Nature of of Light Light
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Anal Chem 251 Lect 5 Spectroscopy 4 THE NATURE OF LIGHT Visible light is one type of electromagnetic radiation. Electromagnetic radiation consists of energy propagated by means of electric & magnetic fields, travels as waves. The classical wave model distinguishes between waves and particles ; The wave nature of light explains: 1. Why rainbows form 2. How magnifying lenses work 3. Why objects look distorted under water
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Anal Chem 251 Lect 5 Spectroscopy 5 THE NATURE OF LIGHT Continued The wave properties of electromagnetic radiation are described by two interdependent variables: 1. Frequency ( µ , Greek nu) is the number of cycles the wave undergoes per second, s -1, also known as Hertz) 2. Wavelength ( λ , Greek lambda) is the distance between any point on the wave and the corresponding point on the next crest or trough. Wavelength is expressed in meters and often for very short wavelengths in nanometers (nm = 10 to the minus 9 meters) In a vacuum, all types of electromagnetic radiation travel at 3.00 x 10 8 m/s, a constant called the speed of light c = λµ Therefore since c is a constant, λ and µ have a reciprocal relationship with each other Radiation with a high frequency has a short wavelength And radiation with a short frequency has a high wavelength
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Anal Chem 251 Lect 5 Spectroscopy 6 Amplitude (intensity) of a wave. Figure 7.2
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Anal Chem 251 Lect 5 Spectroscopy 7 Amplitude of a Wave Another characteristic of a wave is its amplitude, the height of the crest of the depth of the trough of each wave. The amplitude of an electromagnetic wave is a measure of the strength of its electric and magnetic fields Amplitude is related to the intensity of the radiation, which we perceive as brightness in the case of visible light Light of a particular color, fire engine red, has a specific frequency and wavelength but it can be: Dimmer (lower amplitude) Brighter ((higher amplitude)
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Lect 5 Spectroscopy 8 Regions of the electromagnetic spectrum. Figure 7.3
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This note was uploaded on 04/27/2008 for the course CHEM 251 taught by Professor Vassilian during the Fall '06 term at Rutgers.

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Lecture 5 - Lecture 5 Chapter 18: Spectroscopy (Light-...

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