The use of UV excimer lasers at 193nm, 248nm and 308 nm and of tunable UV frequency converted dye lasers in the range 195nm to 308nm for the controlled decomposition of organometallic precurser molecules will be described. Results for metal-alkyls with emphasis on the elements Al, Ga, As, Te and the alkyl ligands CH3, C2H5, i-C4Hg and other ligands H, Cl are presented. We can show, that by proper use of laser wavelength and ligand combination an organometallic precurser molecule can be decomposed into products of interest for surface modification. We shall describe results obtained in the gas phase and when these molecules are in contact to surfaces of practical interest (Si, SiO2, Al2O3 and others). Features of a new excimer laser surface processing and diagnostics machine will be given.