Subnanometer Analysis of Solid Surface by Laser Ablation Atomic Fluorescence Spectroscopy

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We tried to apply the laser ablation technique to the atomizer of the laser atomic fluorescence spectroscopy, and named it LAAF (Laser Ablation Atomic Flu-orescence) spectroscopy. LAAF is one of the most sensitive detection method in the analytical techniques of elements. The purpose of this project is to apply the LAAF spectroscopy to the element analysis of the surface of solid materials and to determine the depth distribution of a specific element with a spatial resolution of less than I nm.The sample is ablated by an ultraviolet laser, and the laser-induced-fluorescence (LIF) from the ablation plume is observed using a tunable laser. The depth distribution of a specific element is determined by repeatedly ablating. Therefore, uniform ablation of a very thin layer is important. Followings are the summary of research results for these two years.1. We tried the ablation of a very thin layer with an order of nanometer or sub-nanometer for various materials such as glasses, polymers, metals, and semiconductors. As a result, we find that subnanometer ablation is possible for glasses and polymers, by using an ArF laser whose fluence is accurately controlled.2. We successfully detected steady LAAF signals from Na atom for glasses and polymers, even in such very thin-layer ablation.3. TUsing a PMMA sample whose Na concentration is known, the spatial resolution and the detection limit is evaluated.4. TThough the ablation of Si is not uniform in the case of the 1Ons ArF laser, uniform ablation is attained using a femtosecond laser.