Starke discovered the transuranic element neptunium (atomic number 93), independently from the American team of Edwin McMillan and Philip Abelson.
Starke subsequently accepted a position to work with the German group at the Paris cyclotron, initially headed by Wolfgang Gentner, from Walther Bothe's Institut für Physik in Heidelberg.
Under Clusius, Starke worked on the German nuclear energy project, also known as the Uranverein (Uranium Club).
It was not until 1944 that Werner Osenberg, head of the planning board at the Reichsforschungsrat, was able to initiate calling back 5000 engineers and scientists from the front to work on research categorized as kriegsentscheidend (decisive for the war effort).
By March 1947, Heinz Maier-Leibnitz, Kurt Stark, and other younger collaborators with Bothe at the Institut für Physik had left for North America.
In 1971, he moved his institute to the premises of the newly created and built Fachbereich Physikalische Chemie (Department of Physical Chemistry), and he was its first Dekan (dean).
The reports were confiscated under the Allied Operation Alsos and sent to the United States Atomic Energy Commission for evaluation.