Demonstrations

Spectral Lines/Spectroscopy - Sodium Absorption

Code Number :	7B11.15
Disclaimer:	Reprinted by permission of Dick Berg, University of Maryland, for use on this website. The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources. Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA. The University of Iowa Disclaimers: University of Iowa Disclaimer All Rights Reserved..
Condition :	Excellent
Principle :	Spectra of Various Gases, Spectral Lines of Elements
Area of Study :	Optics, Astronomy
Equipment :	Slide Projector, Sodium Absorption Apparatus, (Variable slit and lens unit, Fischer Burner Unit), Grill Lighter, Plexiglas Stand for Slide Projector, diffusing screen if desired, and Rock Salt.
Procedure :	The sodium absorption stuff is set up as shown. Observe the distances fairly carefully as it is a critical part of making this work. The lens of the slide projector will need to be turned almost clear out. Light the burners and wait until they burn with a bright yellow flame before putting into the light path. Focus the camera onto the red-yellow end of the spectrum showing on the grating. Note: The burners must be lined up in the light path. The white light spectrum observed will have many streaks in it due to light bulb configurations. To minimize this the use of a diffusing screen is advised. The one that we are using is in a 35 mm slide holder and can be inserted directly into the slide projector.

References

Michael Gore, "Shedding Light on Darkness," TPT, Vol. 45, # 4, April 2007, p. 250.

"Figuring Physics", TPT, Vol. 43, # 2, Feb. 2005, p. 117.

Bruce C. Palmquist, "Interactive Spectra Demonstration", TPT, Vol. 40, # 3, Mar. 2002, p. 140.

Donald F. Collins, "Video Spectroscopy - Emission, Absorption, and Flash," TPT, Vol. 38, # 9, p. 561, (Dec. 2000).

Kenneth Brecher, "Do Atoms Really "Emit" Absorption Lines?" TPT, Vol. 29, # 7, p. 454, (Oct. 1991).

Haym Kruglak, "Apparatus for Displaying Three Types of Spectra", TPT, Vol. 23, # 5, May 1985, p. 314 - 315.

Zenon Gubanski, "Demonstrating the Line Absorption Spectrum of Sodium Vapor", TPT, Vol. 18, # 2, Feb. 1980, p. 140.

"Did Cave Men Ever See a Fraunhofer Spectrum", TPT, Vol. 15, # 2, Feb. 1977, p. 93.

Mary Jane Gary and Victor G. Mossotti, "Nonflame Absorption Spectroscopy: A Technique for Elemental Analysis", TPT, Vol. 13, # 6, Sept. 1975, p. 362.

Edwin Paul Heideman, "Absorption Spectra", TPT, Vol. 9, # 6, Sept. 1971, p. 345.

Robert de Levie, "On Deconvolving Spectra," AJP, Vol. 72, # 7, p. 910, July 2004.

Isaac Asimov, "What Are Little Stars Made Of?" Fantasy and Science Fiction Magazine, pp. 125.

Mail Questions and Comments to: Dale Stille