  Four different techniques were applied for the production of $^{233}$U alpha
recoil ion sources, providing $^{229}$Th ions. They were compared with respect
to a minimum energy spread of the $^{229}$Th recoil ions, using the emitted
alpha particles as an indicator. The techniques of Molecular Plating,
Drop-on-Demand inkjet printing, chelation from dilute nitric acid solution on
chemically functionalized silicon surfaces, and self-adsorption on passivated
titanium surfaces were used. All fabricated sources were characterized by using
alpha spectrometry, radiographic imaging, and scanning electron microscopy. A
direct validation for the estimated recoil ion rate was obtained by collecting
$^{228}$Th recoil ions from $^{232}$U recoil ion sources prepared by
self-adsorption and Molecular Plating. The chelation and the self-adsorption
based approaches appear most promising for the preparation of recoil ion
sources delivering monochromatic recoil ions.
