Even while controversy raged on sub-electronic charges, Ehrenhaft made important and substantial contributions to physics including the demonstration of photophoresis and other effects on the interaction of particles with light. Some of these effects have subsequently been explained in terms of existing phenomena, but some still remain poorly understood. He became professor of experimental physics at Vienna in 1920 and was known as a conscientious researcher and effective lecturer though single-minded to the point of absurdity. Albert Einstein was a frequent visitor to his home. Following the Anschluss in 1938, Ehrenhaft emigrated, first to England, then to the U.S. where he became a citizen.