This thesis comprises both experimental and theoretical studies on transition metal (TM) containing molecules and then mainly on CrF and CrCl. Both the experimental and theoretical parts have been aimed at a depend understanding of the electronic structure.

The experimental part has involved the recording of thermal emission spectra using a Fourier transform spectrometer and the obtained spectra have been analysed using modern data processing strategies.

In the theoretical work, calculations have been done using Ligand-Field-Theory (LFT), Density-Functional-Theory (DFT), Multi-Reference-Configurations-Interaction (MRCI) and Spin-Orbit-Configuration-Interaction (SO-CI).