In order to study mechanism of laser ablation, the time-of-flight spectra of monovalent ions generated by ablation of alkaline earth metals are measured. The obtained spectra show that the ion generation is caused by 5-, 4- and 3-photon processes for Ca, Sr and Ba, respectively, when ArF excimer laser is used as a light source. This behavior suggests that laser ablation of alkaline earth metals is triggered by excitation of electrons at the highest inner-core level. Control of layer-by-layer growth processes by monitoring emission from the ablation plume is also reported. The emission measurement is utilized for estimation of each layer thickness in layer-by-layer growth. This conventional technique is very effective for automatic control of layer-by-layer growth.