Kasha's rule

proper noun

A principle in the photochemistry of electronically excited molecules, stating that photon emission (fluorescence or phosphorescence) occurs in appreciable yield only from the lowest excited state of a given multiplicity.

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Meanings

proper noun
  1. A principle in the photochemistry of electronically excited molecules, stating that photon emission (fluorescence or phosphorescence) occurs in appreciable yield only from the lowest excited state of a given multiplicity.

Origin

Named after American spectroscopist Michael Kasha, who proposed it in 1950.

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Cite this entry
APA

Kasha's rule. (n.d.). In WatkinsX Dictionary. Retrieved November 4, 2026, from https://dictionary.watkinsx.com/word/Kasha's%20rule

MLA

“Kasha's rule.” WatkinsX Dictionary, https://dictionary.watkinsx.com/word/Kasha's%20rule. Accessed November 4, 2026.

Chicago

WatkinsX Dictionary, s.v. “Kasha's rule,” accessed November 4, 2026, https://dictionary.watkinsx.com/word/Kasha's%20rule.

Source: Kasha's rule on Wiktionary, CC BY-SA 4.0.