Laser ablation of CsI analyzed by delayed extraction

Secondary ion emission from polycrystalline CsI irradiated by pulsed-UV laser (337 nm) is analyzed by time-of-flight (TOF) mass spectrometry. Measurements were performed for different laser intensities and for several delayed extraction times (0200 ns). The TOF peak shape is characterized by a Gaussian-like structure (fast component), followed by a tail (slow component) that is more pronounced when the extraction field is delayed. A thermal-sputtering uni-dimensional model is employed to describe the solid surface and plasma temperatures as a function of time. Heat diffusion, vapor photo-ionization, radiative emission and plume expansion are considered. Within the approximations used, the model predicts reasonable drift velocities of the plume (approximate to 1.4 km s(-1)) but very high plasma temperatures (approximate to 10(5) K). The width of the TOF peak fast component allows determination of the plume temperature during its expansion. (C) 2003 Elsevier Science B.V. All rights reserved.