Overhead Projector with Tube of Water and "Vanish"
Spectral Lines
Equipment for Spectral Lines/Spectroscopy Demo
633nm Laser Wavelength Absorbed

 

Code Number: 7B11.85

Demo Title: Spectral Lines/Spectroscopy - Copper Compounds - "Vanish"

Condition: Excellent

Principle: Absorption Spectra of Copper compounds

Area of Study: Modern Physics, Optics, Astronomy

Equipment: 

Overhead slit slide, holographic grating, solutions of "Vanish" which contain copper phthalocyanine.

Procedure:

See also: 7B11.85 in Astronomy

Position the slit slide on the overhead and place the holographic grating in the exit beam.  Place the desired copper compound solution over half of the slit.  In this fashion you will be able to see the regular spectrum and an absorption spectrum.

NOTE: The spectrum will be a molecular absorption (band absorption).

The copper phthalocyanine dye in the "Vanish" should have an absorption band centered around 630 nm, with half-widths of about 20 nm.

An interesting variation is to show the absorption peak using lasers.  In picture # 3 above there are 3 laser pointers.  The top laser pointer has a wavelength of 650 nm, the middle has a wavelength of 633 nm, and the bottom (green) has a wavelength of 532 nm.  When a "Vanish" solution of the proper concentration is placed in the path of the lasers the 633nm (middle or He/Ne wavelength) is absorbed.

References:

  • Yi Jinn Lillian Chen, Jiann-Shing Lih, Tzu-Chun Chen, Jeng-Fung Hung, Jing-Yuan Ko, "Chlorophyll Fluorescence: Visualizing the Inner-Filter Effect", TPT, Vol. 62, #8, Nov. 2024, p. 690.
  • Column Editor's Note, "A Vanishing Act", TPT, Vol. 45, # 3, March 2007, p. 184.
  • Gerard P. Lietz, "A Vanishing Act", TPT, Vol. 44, # 9, Dec. 2006, p. 618.
  • Kenneth Brecher, "Do Atoms Really "Emit" Absorption Lines?", TPT, Vol. 29, # 7, July 1991, p. 454.