Photoelectric observations – however not from surfaces, as in Berlin, but rather in bulk insulators – were started by Pohl together with his assistant Bernhard Gudden in 1919.
Lichtelektrische Beobachtungen – allerdings nicht an Oberflächen wie in Berlin, sondern im Inneren von Isolatoren – begann Pohl mit seinem Assistenten Bernhard Gudden im Jahr 1919.