High resolution L x-ray emission spectra of Fe and Cu have been measured by 0.75 MeV/u H and He, and 0.73 MeV/u He, Si and Ar ion impacts with a crystal spectrometer. The x-ray transition energies in the Fe and Cu targets for Lι, Lη, Lα1,2, Lβ1 and Lβ3,4 diagram lines induced by light ion impacts are determined, which are in good agreement with those given in the reference. The difference in L x-ray emission spectra produced by H, He, Si and Ar ions is considered and the emission spectra for the Cu target are compared with the calculated ones based on the multiconfiguration Dirac-Fock method. The origin of the broadening of the Lα1,2 line to the lower energy for Si and Ar ion impacts is attributed to one 2p plus one 3d electron vacancy production.