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Favorite Demonstration: The Laporte Selection Rule in Electronic Absorption Spectroscopy

Journal of College Science Teaching—November 1999

The Laporte selection rule states that electronic transitions between two gerade (g) states are forbidden; electronic transitions between two ungerade (u) states are forbidden; and electronic transitions between a gerade state and an ungerade are allowed. This can confuse an undergraduate, especially since the source of the intensity reduction may seem hidden in the mathematics. Students who do not grasp the source of the intensity reduction never fail to be impressed by the demonstration described in this article.
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