This work started under the supervision of Wilhelm Wien and continued later in collaborations with Walther Gerlach.
For the first time the problem of light excitation of phosphors by solid canal rays was observed by energy considerations.
With the interaction of matter with canal rays Rüchardt was able to formulate extensive statements on the construction and properties of atoms.
The research included Einstein's rotating mirror experiment (Spiegel-drehversuch) and the Transverse Doppler effect.
He wrote an abstract for the Physikalische Berichte that pointed out that Rupp's vacuum pump appeared in the wrong location.
From this he showed that obtaining the kind of freely decaying atoms that Rupp had claimed to do in his experiments would have been impossible.
[7] In 1935, following Rupp's fall from grace and in the midst of the controversy over what elements of his work could be trusted, Rüchardt and Walther Gerlach published a short note in the Annalen der Physik in which they made very clear that Rupp had confirmed a mistakenly drawn diagram by Albert Einstein.