Answer
Ahmed Zewail received his PhD from the University of Pennsylvania in 1974. He studied physical chemistry under the supervision of Gerhard Herzberg, a Nobel laureate. Zewail's doctoral thesis was on the dynamics of chemical reactions. He was awarded the Nobel Prize in Chemistry in 1999 for his work on femtochemistry, the study of chemical reactions on the timescale of femtoseconds (10-15 seconds).