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Optical Engineering

Primary photochemical process in films of dichromated gelatin: a quantitative approach
Author(s): Christophe Lafond; Christine Pizzocaro; Roger A. Lessard; Michel Bolte
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Paper Abstract

The photochemical behavior of dichromated gelatin films is investigated on irradiation at 365 nm and 491.6 nm. Fourier transform infrared (FTIR) spectroscopy confirms the two-step reduction of chromi- um(VI) into chromium(III). Prior to the irradiation, the molar extinction coefficient ? of chromium(VI) in the film is measured as a function of the pH of the starting solution with the result that e appears to be pH independent in the range 2 to 10 contrary to what is observed in solution. Chromium(V) resulting from a charge transfer between the polymeric matrix and chromium(Vi) species in the excited state appears to be surprisingly stable in the gelatin matrix. Accordingly, the subsequent slow reduction of chromium(V) into the final chromium(III) does not interfer in a significant way in chromium(VI) reduction. As a result, it is possible to determine the UV-visible spectrum of chromium(V) and to quantify its formation. So far no quantitative results were reported in the literature concerning the chromium(V) spectrum and its formation in a film of dichromated gelatin. FTIR spectroscopy confirms the two-step reduction of chromium(VI) into chromium(III).

Paper Details

Date Published: 1 March 2000
PDF: 6 pages
Opt. Eng. 39(3) doi: 10.1117/1.602405
Published in: Optical Engineering Volume 39, Issue 3
Show Author Affiliations
Christophe Lafond, Univ. Laval (Canada)
Christine Pizzocaro, Univ. Blaise Pascal (France)
Roger A. Lessard, Univ. Laval (Canada)
Michel Bolte, Univ. Blaise Pascal (France)

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