Luminescence induced by IRFEL ablation of solid samples

An intense infrared free electron laser (IRFEL) causes laser ablation with an emission of visible luminescence from solids samples. In the case of zinc selenide crystals (ZnSe), the focused IRFEL pulse induces the ablation on the surface because of its high peak power density, despite ZnSe being normally transparent to infrared light. The pulsed IRFELs are at 9.2- and 10.2-μm in wavelength and of several GW/cm2 in power density. The luminescent lines can be identified as the neutral atomic lines originating from the target zinc atoms. The pulsed luminescence from ZnSe is short in width and synchronized with the irradiated IRFEL pulses, which is operated at 22.3 MHz. From the relation of the 9.2-μm FEL fluence and luminescent intensity, the threshold of the ZnSe luminescent emission is found to be ∼13 mJ/cm2 at 9.2-μm IRFEL irradiation. (Copyright (c) 1998 Elsevier Science B.V., Amsterdam. All rights reserved.)