Tjalling Koopmans

I guess it it is well known that the Koopmans that won the 1975 nobel prize
 in economics is also the same person that is quoted in our famous Koopmans
 I was surprised the other day to learn that his past in theoretical
 chemistry is unknowned to the economists. As a matter of fact, here is how
 he presented this period of his life in his nobel prize autobiography
 "in 1930, I switched [from mathematics] my emphasis to theoretical physics
 a timid compromise between my desire for a subject matter closer to real
 life and the obvious argument in favor of a field in which my mathematical
 training could be put to use. [...] Below, I cite my one publication in
 quantum mechanics so that I can add here that Kramers's generosity and my
 inexperience combined to prevent his being listed as co-author of that
 paper. He should have been, because, although the main proposition was my
 own idea, Kramers, besides guiding the writing, also supplied the proof"
 This means that his paper ("Ueber die Zuordaung von Wellenfunktionen und
 Eigenwerten zu den einzelnen Elektronen eines Atoms, "Physica 1, no. 2,
 1934, pp. 104-113) was the only one he ever wrote in the field.
 I know it was not uncommon at the time that people publishing in theoretical
 physics/chemistry were in fact mathematicians, but i am surprised that his
 work seemed so secondary in his career. Could it be that he was even unaware
 of how much he is quoted in theoretical chemistry ?
 Any hints ?
 Alexandre HOCQUET
 Laboratoire de Physicochimie Biomoléculaire et Cellulaire
 ESA CNRS 7033
 hocquet ( ( at ) )
 Fax: 33 1 44277560
 LPBC, case courrier 138
 4 Place Jussieu, 75252 PARIS Cedex 05 France