The L-shell x-ray yields of Zr and Mo bombarded by slow Ar16+ ions are measured.The energy of the Ar16+ ions ranges from about 150 keV to 350 keV.The L-shell x-ray production cross sections of Zr and Mo are extracted from these yields data.The explanation of these experimental results is in the framework of the adiabatic directionization and the binding energy modified BEA approximation.We consider,in the slow asymmetric collisions such as Ar and Mo/Zr,the transient united atoms (UA) are formed during the ion-surface interaction and the direct-ionization is the main mechanism for the inner-shell vacancy production.Generally,the theoretical results are in good agreement with the experimental data.