[en] This thesis describes the formation of electronically excited but translationally cold molecules formed from rubidium atoms and two isotopes of ytterbium (¹⁷⁶Yb and ¹⁷⁴Yb) by means of photoassociation. The experiments were performed in a combined MOT with 10⁹ rubidium atoms and 2.10⁶ ytterbium atoms at temperatures of less than 1 mK. Photoassociation lines were found by trap loss spectroscopy throughout a wavelength range of 2 nm near the 795 nm D1 transition in rubidium. The majority of lines belong to two vibrational series in the excited YbRb^* molecule, converging on a system of a ground state ytterbium atom and an excited rubidium atom. The strong variation of line strength between different vibrational lines is explained through the Franck-Condon principle. An improved version of the Leroy-Bernstein equation was used to extract the leading dispersion coefficient of the potential from the vibrational progression. Most of the observed lines show a resolved rotational structure as expected from a basic quantum mechanical model. The series terminates with the third or forth rotational component due to the ground state centrifugal barrier.The measured rotational constants agree very well with calculations based on the C₆ coefficient. The discovery of a splitting of the rotational components into subcomponents indicates an uncommon angular momentum coupling described by Hund's case. Variations in the depth of the subcomponents indicates a similar splitting in the ground state, with the energies of the substates based on the alignment of the rubidium atom's magnetic dipole moment relative to the angular momentum carried by an approaching ytterbium atom. This creates an additional ground state barrier, partially suppressing some of the subcomponents. Using a rate equation model developed for this purpose, a maximum formation rate of 2.5.10⁶ molecules per second was calculated over the volume of the entire trap. The work presented here is an important step on the way to the formation of molecules that are not only translationally ultracold, but also in the electronic and rovibrational ground state. (orig.)