Mostafa El-Sayed

Mostafa Amr El-Sayed, born May 8, 1933, in Zifta, Egypt, is an Egyptian-American physical chemist. He formulated what is known as the El-Sayed rule, which describes how the spin of an excited electron affects the rate at which a molecule can cross between different electronic states, a principle now standard in the study of photochemistry and spectroscopy. In later decades his laboratory turned to nanoscience, pioneering the synthesis and study of gold nanorods and their optical and catalytic properties, work recognized with the 2007 National Medal of Science; he retired from active research in 2020 after publishing more than twelve hundred papers.