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How a Photon Is Created or Absorbed
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Giles Henderson Eastern Illinois University, Charleston, IL 61920 Robert C. Rittenhouse Walla Walla College, College Place, WA 99324 John C. Wright and Jon L. Holmes University of Wisconsin-Madison, Madison, WI 53706 |
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Note: |
This issue is out of print. How a Photon is Created or Absorbed is averrable online from JCE Internet. |
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How a Photon Is Created or Absorbed is an electronic version of a paper by the same title published in this Journal in 1979 (1). This electronic version operates under Microsoft Windows; a Macintosh version is also available (2). Only minor revisions have been made in the text, but the electronic medium allows the authors to provide interactive graphics and animations that illustrate the points being made much more effectively than could be done in the print medium. Quantum transitions are typically represented by vertical arrows connecting energy levels, and the emphasis is on the requirement that the energy of the photon equal the difference between the two energies represented by two horizontal lines. It is natural for students to wonder what actually happens when a photon is created or absorbed by such a transition, but such questions are seldom addressed. This paper provides a visually interesting and quite striking model of the mechanism of the process. It does so by means of spreadsheet calculations and graphic displays of dynamic quantum trajectories for transitions involving a rigid rotor and a harmonic oscillator, and animations of the behavior of electron density in a hydrogen atom undergoing the allowed 2p to 1s transition and the forbidden 2s to 1s transition. These replace static figures that appeared in the original paper.
This paper is written in Microsoft Word for Windows. Charts from spreadsheets written in Microsoft Excel have been embedded in the Word document to display some of the figures (rigid rotor and harmonic oscillator). The animations of electronic transitions for the hydrogen atom are also embedded in the Word document using QuickTime. Word and Excel are required in order to read the paper. In addition to its pedagogical value relative to enhanced understanding of quantum transitions, this paper pioneers a format that we expect will become more common in the future, namely an electronic document that makes use of graphic and calculation abilities of computers to enable better understanding of an otherwise arcane topic. Hardware and Software Requirements Software in Series D of JCE: Software requires Microsoft Windows version 3.0 or later and associated hardware as defined by Microsoft. We recommend an IBM-PC/AT, PS/2, or compatible computer with a 80386 or higher processor, a minimum of 4 MB of memory, a hard disk, one 3.5-in. floppy disk drive to install the software, a mouse, and a Windows-compatible graphics card (such as an IBM VGA or a SVGA adapter) with a compatible color monitor. DOS version 5.0 or later is highly recommended. In addition to the hardware and software recommended above, How a Photon Is Created or Absorbed requires Microsoft Word for Windows version 2.0 or greater and Excel for Windows version 4.0 or greater. An SVGA graphics adapter with 256-color capability or better is required. Installation of How a Photon Is Created or Absorbed requires about 15 MB of hard disk space. Literature Cited |
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Last Updated: April 26, 2001 Created: December 4, 1996 |
Created by: J. L. Holmes Comments to: jceonline@chem.wisc.edu |
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| © 1997 Division of Chemical Education, Inc., American Chemical Society. All rights reserved. | |