Lasers Chapter 5 - Lasers PH 645/ OSE 645/ EE 613 Summer...

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Lasers PH 645/ OSE 645/ EE 613 Summer 2010 Section 1: T/Th 2:45- 4:45 PM Engineering Building 240 John D. Williams, Ph.D. Department of Electrical and Computer Engineering 406 Optics Building - UAHuntsville, Huntsville, AL 35899 Ph. (256) 824-2898 email: [email protected] Office Hours: Tues/Thurs 2-3PM JDW, ECE Summer 2010
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Chapter 5: Radiative Transitions and Emission Linewidth Molecular Energy Levels and Spectra Liquid Energy Levels and Their Radiation Properties Energy Levels in Solids – Dielectric Lasers Energy levels in Solids – Semiconductor Lasers – See notes from Kasap/Yariv Cambridge University Press, 2004 ISBN-13: 9780521541053 All figures presented from this point on were taken directly from (unless otherwise cited): W.T. Silfvast, laser Fundamentals 2 nd ed., Cambridge University Press, 2004. Chapter 5 Homework: 1, 3, 4, 5, 6, 7, 12, 14
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Atomic and Molecular Bonding Attractive forces between atoms form strong intramolecular bonds as a result of chemical interactions Covalent: carbon-carbon Ionic: sodium-chloride Intermolecular bonding: Van der Walls Ion-Dipole Binding interactions between molecules –Hydrogen bonding Twice as strong as dipole- dipole bonding 2.5-3.5 Ang in length (covalent H- is <2 Ang ) r e Q AQ Be U o r R ionic πε 4 2 2 1 / = A = Madelung Constant Different for each molecule B = quantum constant solved for using Schrödinger ... 3 8 2 12 6 + A Z 1 Z 2 Figure from: Hornyak, Dutta, Tibbals, and Rao, “Introduction to Nanoscience,” CRC Press, Boca Raton, Chapter 10 (2008).
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Types of Intramolecular bonding Ion-Ion and Ion-Dipole Interactions Purely electrostatic Van der Waals Dipole-Dipole interactions Coulombic alignment of two or more permanent dipoles Hydrogen Bonding Extremely strong dipole- dipole interactions Occurs between two highly electronegative and small atoms like O and N and a shared H. Highly directional and quite specific Hydrophobic Interactions Bonding between nonpolar molecules in aqueous solvents Alignment of nonpolar regions changes the shape of the molecule and provides more attachment for polar sections through hydrogen or other intramolecular bonding mechanisms. Repulsive Forces Steric repulsion occurs when electron clouds overlap Hydrophilic repulsion occurs in polar liquids with nonpolar elements in attempt to maximize hydrogen bonding Repulsive entropic elasticity: repulsive forces due to compression of long chain macromolecules Repulsive osmotic: from electrical double layers between two charged surfaces and steric alignment in macromolecules
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As two atoms are brought together, the resulting energy levels of the combined atoms become the energy levels of the molecule formed The median dip in energy associated with the mean binding distance predicted by the Leonard Jones potential of each species
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This note was uploaded on 12/15/2011 for the course OSE 2000 taught by Professor Williams during the Summer '10 term at University of Alabama - Huntsville.

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Lasers Chapter 5 - Lasers PH 645/ OSE 645/ EE 613 Summer...

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