 Under Born and Franck , Göttingen was one of the world 's great centres for physics between 1920 and 1933 . Although they published only three papers together , Born and Franck discussed every one of their papers with each other . Gaining admittance to Franck 's laboratory became highly competitive . His doctoral students included Hans Kopfermann , Arthur R. von Hippel , Wilhelm Hanle , Fritz Houtermans , Heinrich Kuhn , Werner Kroebel , Walter Lochte @-@ Holtgreven and Heinz Maier @-@ Leibnitz . In supervising doctoral candidates , Franck had to ensure that thesis topics were well @-@ defined , and would teach the candidate how to conduct original research , while still staying within the limits of the candidate 's ability , the laboratory 's equipment and the institute 's budget . Under his direction , research was carried out into the structure of atoms and molecules . 
