This note shows that the effect observed in the Schwarz-Hora experiment, in which an electron beam passing through a crystal irradiated with laser light proceeds to a nonfluorescent screen and radiates light the same color as the laser, is probably caused by electron bunching. The crystal provides a sharply defined region of electric field amplitude which makes bunching possible.

• Received 22 June 1970

DOI:https://doi.org/10.1103/PhysRevLett.25.273