7B11.85 - Spectral Lines/Spectroscopy - Copper Compounds - "Vanish"

Code Number:
Demo Title:
Spectral Lines/Spectroscopy - Copper Compounds - "Vanish"
Absorption Spectra of Copper compounds
Area of Study:
Optics, Astronomy
Overhead slit slide, holographic grating, solutions of "Vanish" which contain copper phthalocynanine.

See also 7B11.85 in Modern Physics.

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 phthalocynanine 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.

  • Carlos Eugenio Tapia Ayuga, Alfredo Luis, "Fluorescence in Cola Drinks and Caramel", TPT, Vol. 52, # 1, Jan. 2014, p. 54.
  • 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.

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